Ch2_1 #2

Ch4_1 #1

Ch 14_3 #4

Use first and second laws of thermodynamics to find out the answer

Ch 14_3 #3

Use coeficcient of performance for heat pum used for cooling

Ch 14_3 #2

Use expression for efficiency of heat engine

Ch 14_3 #1

use expression for maximum efficiency for heat engine

Ch 14_2 #4

Use heat efficiency equation to find desired quantities

Ch 14_2 #3

Find out total heat to find the heat efficiency

Ch 14_2 #2

Use constant pressure and constant volume processes to calculate the heat. Pay attention what does the work since you need to put sign properly. For part c calculate initial and final temperatures to decide how much energy changed

Ch 14_2 #1

Use expression for work done by a gas in isobaric process

Ch 14_1 #4

Use conservation of energy/heat law

Ch 14_1 #3

Use the conservation of heat/energy

Ch 14_1 #2

Use ideal gas equation to find initial pressure then use isochoric (constant-volume) process to find final pressure

Ch 14_1 #1

Do determine what process it is look at what stays constant. The use equation for ideal gas to find final temperature and number of moles

Ch 13_3 #4

Use Stefan's law to calculate power. Calculate the total area of the cube properly and convert everything into SI units.

Ch 13_3 #3

Use equation for the rate of conduction of heat across a temperature differenceand use for the temperature of the burner

Ch 13_3 #2

Use equation for the rate of conduction of heat across a temperature difference

Ch 13_3 #1

Look at the graph and understnad what different segments of the line correspond to. Remember to convert into SI units.

Ch 13_2 #4

First find how much heat you need to heat ice to melting temperature, then calculate how much heat needed to warm up water. Where does this heat come from?

Ch 13_2 #3

Problem similar to the problem Ch 13_2 #2

Ch 13_2 #2

Use conservation of energy/heat law. Wrtie down equation for heat lost for copper and the equation for heat gained by water. Solve for T_f.

Ch 13_2 #1

Calculate amount of heat transfered to water in one second. How much water needed to absorb this heat for stated temperature difference?

Ch 13_1 #4

Think where the heat comes from that heats up the thermometer? Calculate the amount of heat needed to heat the thermometer.

Ch 13_1 #3

Use equation for heat, specific heat and temperature

Ch 13_1 #2

Use expression for thermal expansion

Ch 13_1 #1

Use the conversion of Cal to find J. Do not confuse calorie with food calorie

Ch 12_3 #4

For part a) use equation for ideal gas. Psi is not SI units so you have to convert it into correct units.
For part b) use relationship for energy and temperature and not that you asked to calculate the energy per one atom. Does the number you obtain is very small or big? Does it make sense?

Ch 12_3 #3

Use the same formula as before, but remember that nitrogen is diatomic gas and thus you have to use correct molar mass.

Ch 12_3 #2

Recall formula for the rms speed of the atoms or relationship between absolute temperature and rms speed.

Ch 12_3 #1

This an ideal gas process with constant volume. Note that the pressure in tire is gauge pressure rather than absolute pressure.

Ch 11_3 #3

In this problem you have to consider water as viscous fluid. You need to maintain pressure in point P for the water to continue to flow at the other end.

3 comments:

Anonymous said...

Can someone help out? I have no idea how to do this problem

November 14, 2010 8:05 PM

matt said...

I cant figure this one out....Help please

November 15, 2010 12:46 PM

By posting answers your setting up your fellow student for failure on the exam. It sounds trivial but it is true. The equation one has to use is one for flow of viscous fluid.

Ch 11_3 #4

Part A should be straightforward (there was quiz on that in class).
Part B you have to use continuity equation and Bernoulli's principle to find the pressure in the lower pipe. Then calculate the pressure in the water column.

11 comments:

Anonymous said...

What is the continuity equation professor?

November 13, 2010 5:42 PM

Anonymous said...

the continuity equation is A1v1=A2v2
I'm not sure which equations to use for part A?

November 13, 2010 8:01 PM

Anonymous said...

How the hell do you figure out anything for this question? You aren't given any pressures for any part of the pipe, just areas and velocities. How can you figure out the height or even the exiting force of the water?

November 14, 2010 8:06 PM

Erica said...

Part A: pressure of anything exited in air is just atmospheric pressure (Patm)=1.013 kPa.

November 14, 2010 10:30 PM

Anonymous said...

Alright so I used Bernoulli's for part A, got an answer of 145.2 kPa, says incorrect, however when I plug that into part B, and got an answer, THAT was correct?

November 14, 2010 11:15 PM

Anonymous said...

P(atm)=1.013*10^5 Pa

November 15, 2010 8:21 PM

Anonymous said...

i have no idea how to do part b

November 15, 2010 8:52 PM

Anonymous said...

how do we do this. This is frustrating

November 15, 2010 8:53 PM

Anonymous said...

Thank you to all who post answers! These questions are complicated and without help from the professor, or help in the form of really General hints, they suck.

November 15, 2010 9:16 PM

Anonymous said...

i still cant figure out part A..can anyone help with that?

November 15, 2010 9:16 PM

I do not think we can allow straightforward answers - hints and guidance that explain physical meaning on the other hand are welcome. It is easy to put this answer now however it will not help during the exam.

Ch 12_2 #4

This is a constant temperature process for an ideal gas.

Ch 12_2 #3

Recall equation for an ideal gas in the sealed cylinder

Ch 12_2 #2

Find how many moles of water there are and use equation for ideal gas to find volume

Ch 12_2 #1

Use equation for ideal gas

Ch 12_1 #4

Calculate molecular mass of H2O2 then calculate number of moles

Ch 12_1 #3

Recall that oxygen is diatomic gas and water molecule has just one oxygen atom

Ch 12_1 #2

Use formula to relate Fahrenheit to Celsius

Ch 12_1 #1

Recall what is spacing for scale in Kelvins and degrees of Celsius

Ch 11_3 #2

Use a continuity equiation first to find velocity at point 2 (be careful there are 2 outgoing pipes), then use Bernoulli's principle to find pressure.

Ch 11_3 #1

Recall that a flow given as a volume per unit time. Do not forget to convert flow into SI units.
Then find the speed of the flow.

Ch 11_2 #4

Use formula for buoyant force

Ch 11_2 #3

Use formula for buoyant force

Ch 11_2 #2

It may be easier to calculate the height under water and then find out the desired distance.

Ch 11_2 #1

Compare buoyancy of the barge in salt and fresh waters.

Ch 11_1 #4

Think why is mercury higher on the side of the box. Recall hydrostatic pressure in for liquid in equilibrium.

Ch 11_1 #3

Use formula for liquids to calculate the pressure.

Ch 11_1 #2

Think what makes the water raise in the straw? What pressure is needed to maintain that?

Ch 11_1 #1

Use mass density formula to calculate unknown quantity

Ch10 3 #4

Recall general formula for Dopler effect and think how many times it occurs

Ch10 3 #3

Recall the formula for beat frequency and find out what frequency actually sound

Ch10 3 #2

Think what waves lengths are allowed for the standing longitudinal waves in air columns

Ch10 3 #1

Recall the formulas for the standing longitudinal waves in air columns

Ch10 2 #4

How does the frequency depend on length?

Ch10 2 #3

You can figure out the answer for the fundamental mode, and then figure out which overtone is shown

Ch10 2 #2

This uses the Doppler Effect to shift the frequency

Ch10 2 #1

See sheet 20

Ch10 1 #4

See the sheets on intensity, especially sheet 9.2

Ch10 1 #3

See sheet 9.5 for the definition of dB

Ch10 1 #2

See sheet 4

Ch10 1 #1

Use the speed of sound, and compute the times from the different distances the sound waves travel. Why are the distances different?

Ch9 3 #4

This a resonance question, and you are tapping at the resonance frequency. Why must this be the resonance frequency?

Ch9 3 #3

This is most easily done using conservation of energy

Ch9 3 #2

This is essentially the generalization of the previous problem.

Ch9 3 #1

Remember that total energy is conserved, and figure out when either KE or PE is zero. When KE is zero PE must be its maximum and vice versa

Ch9 2 #4

CH9 2 #3

See section 9.2.3

Ch9 2 #2

The intermediate step in this problem involves finding the period of the oscillation from the information given.

Ch9 2 #1

See sheet 14 and use Newton's 2nd law, F = ma.

Ch9 1 #4

Use the definitions on sheets 4 - 6.

Ch9 1 #3

Use the basic definitions.

Ch9 1 #2

Ch9 1 #1

Remember that a positive value means "up".

Ch8 3 #4

Ch8 3 #3

The stick isn't moving, so the sums of all forces and all torques must both be zero.

Ch8 3 #2

Ch8 3 #1

This problem is like the conservation of energy problems in Ch6, but now there is also kinetic energy of rotation, equation 8.15

Ch8 2 #4

Ch8 2 #3

Use equation 8.12. What is the moment of inertia for a cylinder?

Ch8 2 #2

The "net torque" is the sum of all torques. Remember the opposite rotation directions have opposite signs.

Ch8 2 #1

Use equation 8.10. Make sure to use the perpendicular distance between force and pivot.

Ch8 1 #4

This problem is very much like the previous problem and uses the same basic ideas. Do you see why?

Ch8 1 #3

Use the rotational analogies for linear motion in constant acceleration. The rotational forms are equations 8.7 - 8.9

Ch8 1 #2

Decide if any of the quantities, angular or linear, must be the same for both people by using the picture without any math needed. Then use definitions like equation 8.3.

Ch8 1 #1

Ch7 3 #4

Ch7 3 #3

Watch out to not confuse "elastic" and "inelastic"

Ch7 3 #2

CH7_3 #1

Ch7 2 #4

In addition to Ch7 momentum conservation, you'll need the work-energy theorem from Ch 6. The friction does work to slow the block down. Do this problem in two pieces: (1) immediately before and immediately after the collision, and (2) while the block slows down.

Ch7 2 #3

Ch7 2 #2

Ch7 2 #1

See Ch7 example 7.2

Ch7 1 #4

See Ch7 sheet 11

Ch7 1 #3

Break these problems into parts corresponding to each value of the force. (Right is moving in the positive x direction.)

Ch7 1 #2

The change in momentum is the difference between final and initial momentum

Ch7 1 #1

See Ch 7 sheet 3

Ch6_3 #2

See Ch 4 Sheet 24, Ch 6 Sheet 19' and 28.

Ch6_3 #4

Se Ch 6 Sheet 15. Here in addition to gravity the frictional force in the atmosphere does work Wfr and equation (6.4) on Sheet 15 holds. See on Ch 6 Sheet 18 how you can write the same equation in terms of the total mechanical energy E = KE + PE with the conservation of E being E2 - E1 = 0. With friction the energy loss is Wfr = E2 - E1.

Ch6_3 #3

See Ch6 Sheet 24 for the exact expression of the Gravitational Potential Energy. Use it to calculate the change in potential energy, the difference in potential energy for the 2 positions. Compare this with mgh, which is an approximate change of the potential energy neglecting the variation of g along the path of the object (See Ch 6 Sheet 24').

Ch6_3 #1

See Ch6 Sheet 8 and 28.

Ch6_2 #4

See Ch6 Sheet 5, 28 and 31. Here the motion is vertical.

Ch6_2 #3

See Ch6 Sheet 18'. There is no friction. What matters, the distance along the inclined plane or the vertical distance ?

Ch6_2 #2

See Ch 6 Sheet 13 and 15.

Ch6_2 #1

See Ch 6 Sheet 3. What is the angle between the head-force and the displacement ?

Ch6_1 #4

See Ch 6 Sheet 8.

Ch6_1 #3

See Ch6 Sheet 8.

Ch6_1 #2

See Ch 6 Sheet 12. Watch out, Death Valley is below sea level.

Ch6_1 #1

See Ch6 Sheet 3.
Part A: Is there a displacement x here ?
Part B,C: Make a sketch. Watch the angle ! The work is on the boy.

Ch5_3 #4

See Ch5 Sheet 30 and 31.

Ch5_3 #3

See Ch 5 Sheet 12. Replace the circle shown by the equator and visualize the man standing on the equator. The pole is the center of the circle. The man is held in orbit by the Centripetal Force which is the vector sum of the Normal Force by the earth on the man and the gravitational force . Write down this vector equation paying attention to the relative signs of the vectors. The apparent weight is the Normal Force.

Ch5_3 #2

See Ch 5 Sheet 26 and the algebraic equation under "Note" in Ch5_3 #1. What do you set g' equal to ? Solve for h.

CH5_3 #1

See Ch 5 Sheet 26. Write down the difference deltag = g_e - g' with g_e and g' replaced by their corresponding expressions on Sheet 26. (deltag is the given numerical value). Note that you can write for the expression for g': GM/(Re+h)^2 = (GM/Re^2)/(1+h/Re)^2 = g_e/(1+h/Re)^2. Use this and solve for h.

Ch5_2 #4

Part A: See Ch 5 Sheet 19. The problem here is, as in the notes, for zero banking angle and only friction supplying the centripetal force.
Part B: See Ch 5 Sheet 17. The problem here is, as in the notes, with no friction and only the horizontal component of the Normal Force, exerted by the road on the car, supplying the centripetal force.

Ch5_2 #3

See Ch 5 Sheet 14'. Assume that the space station is far away from any gavitational pull as in the notes.

Ch5_2 #2

See Sheet 12 and replace the box at the bottom with the ball, held in orbit by the Centripetal Force which is the vector sum of the tension in the string and the gravitational force at the bottom of the circle. Write down this vector equation paying attention to the relative signs of the vectors. The apparent weight is the force of the support on the object, the tension in the string. Take the direction of the centripetal force as positive. Solve for the speed.

Ch5_2 #1

See Sheet 12 and replace the box at the top with the car inside the circle, held in orbit by the Centripetal Force which is the vector sum of the Normal Force by the track and the gravitational force at the top of the circle. Write down this vector equation paying attention to the relative signs of the vectors. The apparent weight is the Normal Force. Set it equal to the regular weight ("true" weight). Take the direction of the centripetal force as positive. Solve for the speed. Watch out , the diameter of the loop-the-loop is given, not the radius.

Ch 5_1 #4

See Sheet 4.

Ch5_1 #3

See Ch5 Sheet 4 for the centripetal acceleration for part A. The velocity of the hand and thus the ball at the time of release is given.

For part B see Sheet 10.

Ch5_1 #2

Convert the rpm (= revolutions per minute) into radians/sec. Multiplying by t gives you the angle swept through in radians. What do you have to do with the initial angle ?
Don't forget that the problem asks for an answer between 0 and 2pi.

Ch5_1 #1

See Ch 5 Sheet 4 for the definitions of Period, Frequency, linear velocity at a given radial distance fron the center, angle swept through for a full circle (which is the same as a "rev" (revolution)) in radians (see Sheet 3 for the definition of a radian).
Part A: You can leave the "rev" and simply divide the two given quantities, the # of rev and the rev/sec.
Part B: Use Sheet 4.

Lab 4 Prep #4

Lab 4 Prep #3

Lab 4 Prep #2

Lab 4 Prep #1

Ch6: Comments on Lecture Notes only

Ch5: Comments on Lecture Notes only

Ch4: Comments on Lecture Notes only

Ch3: Comments on Lecture Notes only

Ch5_3 #3

See Ch 5 Sheet 12: Replace the circle made by the airplane by the equator
which spins about an axis through the center of the circle and perpendicular to the paper plane. Visualize the black rectangle being the person standing on the equatuator. On Sheeet 12 the expression Wapparent = m(g-a_c) with the vectors g and a_c is a generally valid expression for any relative orientation of the vectors. In the case of the person on the equator the vectors g and a_c are parallel to each other, i.e. the expression without vector signs is Wapparent = m(g-a_c) where g and a_c are now magnitudes of the accelerations. At the pole there is no rotation and thus no centripetal acceleration a_c and Wapparent = mg there. For Part B you take the difference between mg and Wapparent at the equator.
You have to calculate a_c as given on Sheet 4 using the circumference of the equator and the daily period of rotation.

Ch4_3 #4

This is a carbon copy of Example 4.5 in Ch 4 Sheet 31.

Ch4_3 #3

This question is a simpler version of what is done in Ch4 Sheet 32, but the basic principle is the same: for the red dot on Sheet 32 not to move the 3 forces have to add up to zero net force. Ditto for the 3 forces in the question here.
The tensions are active as shown below:

Add the force vector components with their appropriate sign (!) to yield a net x-component = 0 and net y-component = 0 (see Ch 3 Sheet 6 extended to 3 vectors).

Ch4_3 #2

See Ch 4 Sheet 19. Example 4.3 is very similar to the question here,
with the exception that here friction is included. ("Kinetic" friction refers to a moving object sliding on a surface, "static" friction refers to an object at rest on a surface. We do not distinguish between the two in this course and simply refer to friction.) Watch out how you use the labels m1 and m2 relative to the question here when you inspect equations in Example 4.3 ! The easiest way to proceed is to add the frictional force to the parallel weight component in the equation at the bottom of Sheet 23 with the correct sign (!) and solve for the mass asked for.
The expression obtained there is the application of Newton's Law II for the combined system (m1 + m2). I recommend strongly to study the procedure on Sheet 21 which yields the tension T in addition to the acceleration a (e.g. in case the tension T is asked for.)

Ch4_3 #1

See Ch 4 Sheet 20. There you have the expression for the weight component of the block parallel to the inclined plane given. Thus you know it in the question here for both blocks. Those 2 weight components make up the net force on the system of 2 blocks taken together. What do you know about the net force since the system is at rest ?

Ch4_2 #4

See Ch 4 Sheet 27. Replace the block by the land rover and see Sheet 28.
Warning! To simply use the solution on Sheet 28 to get the coefficient of friction will work for you but would be a silly short cut. You will be required in the exam to understand the equations on Sheet 26, so study Example 4.4!

Ch4_2 #3

See Ch 4 Sheet 19: turn the inclined plane such that it is horizontal (the 30 degrees go to 0 degrees.) and introduce friction (see Sheet 24) between the bottom of block A and the supporting surface. See Sheet 21 equation (2). How do you have to modify that equation to be valid for your block B (Hint: B moves with constant velocity. Is there an acceleration ?) ? What does your modified equation (2) say about the tension T in the string, which is also the tension pulling on block A ? The tension T acting on block A and the frictional force acting on it together make up the net force acting on block A which moves with constant velocity too. What is then the net force on A ? Write down your condition for this net force. You need to express the frictional force as is done on Sheet 24 using for the Normal Force Sheet 11. You obtain an equation where all variables are known except the coefficient of friction asked for. Solve for it.

Ch4_2 #2

See Ch 4 Sheet 18" for the case when an object is suspended (instead of sitting on a support (see Sheet 18')).
Part B: does the given velocity matter ?

Ch4_2 #1

See Ch 4 Sheets 16,17,18 for the Apparent Weight of on object. You don't have to convert the "lb" into SI units. When you set up the ratio the apparent weight when the elevator accelerates over the apparent weight when the elevator is at rest the units of the weight drop out. How about the mass m ? Solve the resulting equation for the acceleration.

Ch4_1 #4

See Ch 4 Sheet 8,10,11 for Part A.
See Ch 4 Sheet 13 for Part B.

Ch4_1 #3

See Ch 4 Sheet 6 for Newston's Law I.

Ch4_1 #2

See Ch 3 Sheet 6 and extend the formulae from 2 to 3 vectors. See Ch 4 Sheet 5 for the component treatment of Newton's Law II.

Ch4_1 #1

See Ch 3 Sheet 7,8 for the "Head-To-Tail" Rule for vector addition. See Ch 4 Sheet 5 the sketch for a vector sum of forces. You add the 2 forces together and then balance the resulting sum vector with a 3rd vector.
The vectors in Mastering Physics are treated as done in Ch 3_1 #4 (bottom):
In order to manipulate the vector F
1. Click on vector F
2. Click “add vector”
3. Select “unlabelled vector”
4. With the cross hair draw a vector on top of F
6. Manipulate the vector you drew

Lab 3 Prep #5

.

Lab 3 Prep #4

This is equal to what you did already in Lab 1 #5.

Lab 3 Prep #3

Lab 3 Prep #2

Lab 3 Prep #1

The missing figure is

It is essentially the sketch for horizontal launch in Ch 3 Sheet 25'. See Ch 3 Sheet 19 (the equations for Projectile Motion). The first 3 entries are all given. Customize them for the situation here (horizontal launch.)
For the 4th entry consult the Introduction in the Lab 3 Manual. You should, however, be able to derive this relation from your previous correct entries.

Lab 2 Prep #7

There is a missing figure which you don't really need. The hints in the text of the question tells you what to do. What is the constant factor "a" in (1.3) in your case where v=(1/t)d ? How do you convert a relative error into an absolute error (see (1.4))?

Lab 2 Prep #6

The error writeup equation (1.3) will get you to the result. Easier is equation (1.1): what is the constant factor "a" in (1.1) in your case, where d=D/N ?

Lab 2 Prep #4,5

See Ch 2 Sheet 5' (after the sheet with 5 and 5" on it):
Notice that the blue curve is the position x as a function of time:x = x(t), and that x(t) given on Sheet 7 is an example similar to the blue curve. Consult Sheet 5 for the slopes. Consult Sheet 13 and 14 for the expressions giving x(t) and v(t). Notice further that the acceleration is positive and constant.

Lab 2 Prep #1 to #3

See Ch 2 Sheets 13,14,15.
Mislabelled as Sheet 14 for question 1 and 3.

Ch3_3 #4

You should never attempt a projectile motion problem without having the 5 equations on the bottom half of Sheet 27 in front of you. I strongly recommend to make a sketch as on Sheet 21 in Ch3 and enter all given quantities from the problem here into it. This should include your knowledge of the y-component of the velocity at the top of the trajectory. It will be helpful to replace the green vector close to the end of the trajectory by a line representing the net.
Part A:
How do you judge whether the ball clears the net ? Think in terms of the y-component of the ball position at the location of the net. Can you calculate its value ?
(Hint: get the flight time first from the x-equations after you have identified all the given quantities for the horizontal motion. Then use it to calculate the vertical position of the ball at the net.)

Ch3_3 #3

You should never attempt a projectile motion problem without having the 5 equations on the bottom half of Sheet 27 in front of you.
Part A:
Visualize in the example on Sheet 21 y0 = 0 for the case here (the golf ball is hit from the ground.) Can you calculate the y-component of the initial velocity from the data given ? What do you know about the y-component of the velocity at the top of the trajectory ? Given those two can you get the rise-time by going "shopping" among the y-equations ? What do you think is the relation of the rise-and fall-time and thus the total flight time ?
Part B:
Can you get the horizontal distance from Part A and going "shopping" among the x-equations ?
Part C:
If you followed the hints in Part A you found the equation which gave you the flight time. Did it contain the gravitational acceleration ? What is then the flight time on the moon ? What would the horizontal distance be for that flight time ?

Ch3_3 #2

You should never attempt a projectile motion problem without having the 5 equations on the bottom half of Sheet 27 in front of you.
Part A:
What is the y-component of the initial velocity when the rifle is aimed horizontally (See Ch 3 Sheet 25') ? Go "shopping" among the y-equations to get the "sinking-time" the bullet takes to traverse the change in the y-component of the position.
Part B:
Go "shopping" among the x-equations to get the x-component of the initial velocity.
Is the speed, i.e. the magnitude of the full initial velocity vector, different from only the x-component of the initial velocity ?

Ch3_3 #1

You should never attempt a projectile motion problem without having the 5 equations on the bottom half of Sheet 27 in front of you.
See Ch 3 Sheet 25': Visualize the plane attached to the horizontal blue launch vector. When you drop the package what is the initial velocity of the package (magnitude and direction: notice that the package flies with the same velocity vector as the plane). Get the fall-time from the "appropriate" y-equations for the "sinking" motion in the vertical direction (go "shopping" among the equations).
Then get the horizontal distance between the point on the ground where the package was launched and the point on the ground where the package landed from the "appropriate" x-equation (go "shopping" among the equations).

Ch3_2 #4

You should never attempt a projectile motion problem without having the 5 equations on the bottom half of Sheet 27 in front of you.
Part A and B:
See the example Quiz 3.3 on Sheet 25'. Does the fall - time depend on the horizontal component of the initial velocity ?
Part C and D:
Once you have the fall-time how do you get the horizontal distance ?

Ch3_2 #3

See Ch 3 Sheet 16''': the sketch on the left and the example on Sheet 16 is the case
of this problem. The ducks head at a appropriate angle into the wind, such that they actually fly due South. (If you rotate the figure on Sheet 16 or 16''' by 180 degrees you have the directions as given in the problem here.) The solid vectors give the velocity vectors relative to the ground, i.e. Vbg ("b" for bird) is the velocity vector pointing where the birds actually goe - not where they head which is the direction of the dashed velocity vector Vbw ("w" for wind). Identify the 2 given velocity vectors in your problem, make the sketch as on Sheet 16''' and place the velocity values given into the sketch. As is describesd on Sheet 16'' the triangle with a right angle in it allows the application of your "SOHCAHTOA" right away to get the angle, without going through the detailed setup of the vector equations on Sheet 16'. Notice that you need your calculator set to degrees in order to get the angle in degrees as asked for.

Ch3_2 #2

Part A:
See the sketch on Ch 3 Sheet 16''' on the right side of the sheet (there is no video for that sheet): in your problem Mary heads the boat straight across the river, which flows east and thus pushes Mary downstream. (The solid vectors give the velocity vectors relative to the ground, i.e. Vbg is the velocity vector pointing where Mary actually goes - not where she heads the boat which is the direction of the dashed velocity vector Vbw). Identify the 2 given velocity vectors in your problem, make the sketch as on Sheet 16''' and place the velocity values given into the sketch. Notice that d is the change of position in the y-diredtion. Thus you need to use the velocity in the y-direction to get the crossing time.
Part B:
Notice that the distance downstream is the change of position in the x-diredtion. Thus you need to use the velocity in the x-direction to get the distance downstream.

Ch3_2 #1

See Ch 3 Sheet 13,14,14'. You have to modify the equation on sheet 14' such, that the velocities, added with the appropriate relative sign , and the travel time give the travel distance. You do this twice, for the trip down the river, then the return. You obtain 2 equations with 2 unknowns, the velocity of the boat relative to the water (Vbw: Part B) and the velocity of the water relative to ground (Vwg: Part A). The latter is being asked for. Watch out for the relative sign of the velocities on the trip up the river! You solve the 2 equations for the 2 unknowns by substitution.

Ch3_1 #4

See Ch 3 Sheet 7,8,9.

Ch3_1 #3

See Ch 3 Notes Sheet 6 and 4.

Ch3_1 #2

See Ch 3 Notes Sheet 3 and 4.
Part D: Watch out where you are asked to place the angle !

Ch3_1 #1

See Ch 3 Notes Sheet 3 and 4.

Ch3_1 #4

For the vector problem:
1. Click on vector A
2. Click “add vector”
3. Select “unlabelled vector”
4. With the cross hair draw a vector on top of A
5. Repeat the same for B
6. Add Vector
7. Select D and draw it

Ch2: Comments on Lecture Notes only

Post comments here if they pertain to concepts in the notes. If your comment is in reference to a quiz question post it there.

Ch1: Comments on Lecture Notes only

Post comments here if they pertain to concepts in the notes. If your comment is in reference to a quiz question post it there.

LAB 2 Acceleration Manual

Lab 1 #7

See Error, Uncertainty and Graphs . You will need equations (1.2), (1.4) and (1.8).

Lab 1 #6

See Error, Uncertainty and Graphs: Propagation of Errors, addition or subtraction . For the first part note: the time measured is the difference of 2 time measurements T1 at the begin and T2 at the end. Which expression in Propagation of Errors gives the error of this difference when you use the errors for T1 and T2 given ? For the second part see "Absolute Error" (1.1).

Lab 1 #5

See Error, Uncertainty and Graphs: Propagation of Errors . Consult the expressions (1.5,...).

Lab 1 #4

See Error, Uncertainty and Graphs: Propagation of Errors .
Is the absolute error given valid for the radius ? What is the power n in equation (1.8) in your case ? Is the error given divided by the diameter valid for the relative error of the radius ? Is the relative error of r^3 the same as the relative error of[(4/3 pi) r^3] (see equation (1.3)) ?

Lab 1 #3

See Error, Uncertainty and Graphs: Propagation of Errors .
Perimeter: Is your propagation for an addition/subtraction or multiplication/didvision ? Are the errors given for length and width absolute or relative ?
Area: Is your propagation for an addition/subtraction or multiplication/didvision ? Can you use the errors given in your propagation formula as they are or do you have to convert them ?

Lab 1 #2

See Error, Uncertainty and Graphs: Systematic Error

Lab 1 #1

See Error, Uncertainty and Graphs: Random Error

Ch2_3 #4

Part A,B: Use the formula given in the problem text for the height h twice, for the moon and the earth.
Part C: Assume the ball starts from ground. What is the velocity at the highest point of the tyravel ? See Ch2 Sheet 13 for the equation which gives you the rise time. Solve for the rise time. Is the rise time different from the fall time ?
Write the equation for the solution of the rise time down twice, for the earth and for the moon and get the ratio of the two times.

Ch2_3 #3

The acceleration of the elevator is the sum of the motor and gravitational acceleration, the net acceleration.
Part A: See Ch2 Sheet 15 to get the accelaration distance d1.
Part B: Do d1 and d2 in the sketch differ ? Get the distance d in the sketch where the elevator moves with constant velocity from the total distance, d1 and d2. Get the time t in the sketch from d and the constant velocity.
See Sheet 13 to get the acceleration time t1. Do t1 and t2 in the sketch differ ?
Get the total time.

Ch2_3 #2

Part A:
See Ch2 Sheet 21 which describes the travel of the ball launched upward and then back to the level of the students hand. What is the only acceleration present ? Is this acceleration the same at any given time of the travel ?
Part B:
See Sheet 22. After the ball A, launched upward, has reached the students hand again, what is its velocity at that point, magnitude and direction, compared to the initial velocity when ball B is launched downward ?
What do you conclude then about the velocities of ball A and B when they reach the ground ?

Ch2_3 #1

One way to do this: Before she reacts she continues a distance d1 with her initial velocity for the duration of her reaction time: see Ch 2 Sheet 14 for the expression for d1. What is the acceleration during this part of her travel ? When you have d1 get the remaining distance d2 she has available. During the 2nd part of her travel
she has to stop after she has traveled d2. See Sheet 15 and get the distance traveled while decelerating. Do you have all input variables to calculate the stopping distance (x-x0) ? What is your criterion when judging whether she can stop ?

Ch2_2 #4

See Ch2 Sheet 15. What is the sign of the acceleration ?

Ch2_2 #3

Part A: Ch2 Seet 13. Watch the units! See Ch 1 Sheet 4. Lear how to do conversions systematically.
Part B: The fraction of x of y = x/y. g is the gravitational acceleration.
Part C: See sheet 14. Do you know v0, a and t ?
Part D; if you don't know the value of units google them.

Ch2_2 #2

Part A: See Ch2 Sheet 13.
Part B: See Sheet 14. What does "from rest" mean for initial velocity v0 ? How can you express the distance d traveled using x and x0 (see Sheet 15')?

Ch2_2 #1

Part A: Ch2 Sheet 14 gives you the position as a function of time for constant acceleration (2.6). How do you know from the shape of the velocity vs time plot shown that the acceleration is constant ? What is x0 in this problem ? What is v0 ?
How do you get the acceleration a from the graph including its sign (see Sheet 11) ? Once you have x0, v0 and a you get x at 2 s, 3s and (Part B) 4 s.
Part D: If the car changes direction what would the value of the velocity at that point in time be? Do you see such a point on the graph ?

Ch2_1 #4

Part A:
See the Notes Ch2 Sheet 3". The blue curve is the accelerated case.
Part B: On the Sheet after Sheet 5", if you "hang" the green triangle
from the red curce (constant velocity case) you measure the constant slope. See on Sheet 5 how slope of the x-t-graph and velocity are related. The green triangle "hung" from the blue curve (accelerated case) shows you how to measure the average slope between 2 time points. Apply these slope-measurements to the 4 figures and don't forget to consider the sign (+ or -) of the slope when making your judgement.

Ch2_1 #3

See Ch2 Sheet 3. Calculate the time it takes for runner 1, then for runner 2 and take the difference. Notice that the the units of the answer are minutes.

Ch2_1 #1

You need to learn the prefixes (click "Resources", go to the table of "Common Prefixes"). See the Ch1 Notes Sheet 2 for the S.I. units. Consult Ch 1 Sheet 4 for a systematic way to do conversions.
Re "Significant Figures" see Ch1 Sheet 9.
For the connection between speed and distance traveled see Ch2 Sheet 4' , for velocity and displacement see Ch2 Sheet 3.
If you forgot the formula for the volume of a cylinder google it.

Introduction to Mastering Physics

It is strongly recommended to familiarize yourself with the input format of answers into Mastering Physics by doing the "Introduction to Mastering Physics" assignment.