Physics 213 Test 2 12 Points Each October 22, 1997

1. Draw a motion diagram for an object that has : (don't forget your frame of reference.)

a) Positive velocity and negative acceleration.

b) Negative velocity and positive acceleration.

2. 1. A hot air balloon is traveling vertically upward at a constant speed of 5.00 m/s. When it is 30 m above the ground, a package is dropped from the balloon.

Motion Graphs: Motion Diagram & ERF Motion information: Events?

3. An object moves in such a way as to produce the velocity vs. time graph below. If it starts at the origin:

a) At which of the lettered times is the object the furthest

from the origin?_______

b) At which of the lettered times is the object moving the

fastest? ________

c) Is the object moving away from or toward the origin

between times A and B? _____________

d) Describe the object's motion at time C.

4. What is the launching speed of an object shot straight up if it only took 2 seconds to reach its maximum height?

a. 10 m/s

b. 20 m/s

c. 30 m/s

d. 40 m/s

5. A rope with tension T gently pulls a cart, initially at rest along a horizontal frictionless surface. At the instant the carts speed becomes 20 m/s, the tension is reduced T/3. Draw a velocity vs time curve and a motion diagram for the cart, then explain very carefully in words what happens to the speed of the cart.

6. A miner pulls a wagon of supplies to the top of a hill where he lives by hanging from a rope attached to the wagon. As the cart moves at increasing speed up the hill, the miner moves with increasing speed downward. Draw a motion diagram for the miner to determine the acceleration, then draw a free body diagram for the miner , then state which is largest, T or the miner's weight ?

7. The figures below depict eight identical 60 kg people riding eight identical elevators. Each elevator is moving in the direction of the arrow on its right. The reference frame for each of these pictures assumes that up is the positive direction, so a negative acceleration implies a downward acceleration. Give the highest rank to the person whose scales registers the most weight, and the least rank to the person whose scales registers the least weight. Give the same rank to those with equal weight. (Use acceleration due to gravity g = 10 m/s2.)

Highest 1_____ 2_____ 3_____ 4_____ 5______ 6 ______ 7 ______ 8_______ Lowest

Which scales read 0 ?_______.

Please carefully explain your reasoning:

8. Construct a free-body diagram for mass m as it moves up the incline&emdash;mass M moves down the incline. All surfaces have a small amount of friction.