Sunday, August 29, 2010
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 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)) ?
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 ?
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 ?
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.
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 ?
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 ?
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 #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.
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')?
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 ?
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.
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.
Tuesday, August 24, 2010
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.
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
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