Questions 1 - 2 refer to a situation in which 5 wooden blocks (a, b, c, d, and e) are on a table top as illustrated. The vectors shown indicate the relative velocities of the blocks. Assume we can ignore any energy losses due to friction or air resistance.
va = 2.5 m/s
vb = 1.0 m/s
vc = 3.0 m/s
vd = 1.0 m/s
ve = 0 m/s
ma = 2.5 kg
mb = 5.0 kg
mc = 1.5 kg
md = 2.5 kg
me = 10.0 kg
1. Which block has the largest magnitude of linear momentum?
(a) a (b) b (c) c (d) d (e) e
2. What block requires the largest force to speed up from rest to the velocity indicated in 2.5 seconds?
(a) a (b) b (c) c (d) d (e) e
3. Which of the following individuals described below does the most work? Ignore friction for all cases.
a. Kelsey who exerts a force of 600 N on a stationary car that won’t move in 2.0 seconds.
b. Jarrod who lifts a 46 kg box to a height of 2.0 meters off the ground in 5.0 seconds.
c. Mark who pushes a crate across the floor 1.5 meters with a force of 550 N in 3.0 seconds.
d. Katie who pushes a crate (m = 50 kg) with a force of 300 N along an incline a distance of 3.5 meters (along the incline) in 4.0 seconds.
e. Kelly who pulls on a cart (mass = 25 kg) with a force of 400 N at an angle of 30° (relative to the horizontal) through a horizontal distance of 3.0 meters in 4.5 seconds.
Questions 4 – 5 refer to a situation in which two Pascar carts on a dynamics track are involved in an elastic collision. A blue Pascar (mass = 0.750 kg) with an initial velocity of +0.350 m/s collides with a red Pascar (mass = 0.250 kg) which is initially at rest. After the collision, the velocity of the red Pascar is +0.525 m/s. Assume that friction can be ignored.
4. What is the velocity of the blue Pascar after the collision?
a) - 0.117 m/s b) 0 m/s c) +0.375 m/s d) +0.525 m/s e) +0.350 m/s f) +0.175 m/s
5. Which of the following statements for this collision is correct?
a) Only linear momentum is conserved.
b) The red Pascar experiences the same magnitude of the change in linear momentum as the blue Pascar.
c) The blue Pascar exerts a force on the red Pascar but the red Pascar doesn’t exert a force on the blue Pascar.
d) The blue Pascar exerts a larger force on the red Pascar than the red Pascar exerts on the blue Pascar.
e) The red Pascar exerts a larger magnitude of impulse on the blue Pascar than the red Pascar exerts on the blue Pascar.
f) The isolated system includes only the blue Pascar and the track since the red Pascar was not initially moving.