Physics 2

A deer with a mass of 146 kg is running head-on toward you with

a speed of 17 m/s. You are going north. Find the momentum

of the deer.

P= mv

• 2 x 10³ kg•m/s to the north

• 3.5 x 10³ kg•m/s to the south

• 2.5 x 10³ kg•m/s to the south

• 2.5 x 10³ kg•m/s to the north

A 0.50 kg football is thrown with a velocity of 15 m/s to the right. A stationary

receiver catches the ball and brings it to rest in 0.020 s. What is the force exerted

on the ball by the receiver?

F = mvf − mvi

Δt

• 3.8 x 10² N to the left

• 3.8 x 10² N to the right

• 3.8 x 10⁴ N to the left

• 3.8 x 10³ N to the right

A 2240 kg car traveling to the west slows

down uniformly from 20.0 m/s to 5.00 m/s. How long does it take

the car to decelerate if the force on the car is 8410 N to the east?

Δt = mvf − mvi

F

• 3 s

• 2 s

• 4.5 s

• 4 s

An 85.0 kg fisherman jumps from a dock into a 135.0 kg rowboat at rest on the west

side of the dock. If the velocity of the fisherman is 4.30 m/s to the west as he leaves the dock, what is the final velocity of the fisherman and the boat?

v²_f = −m₁ ( v_1f )

m₂

• 1.64 m/s to the west

• 1.64 m/s to the east

• 2.66 m/s to the west

• 3 m/s to the east

A 1500 kg car traveling at 15.0 m/s to the south collides with a 4500 kg truck that is

initially at rest at a stoplight. The car and truck stick together and move together

after the collision. What is the final velocity of the two-vehicle mass?

vf = m₁ v _1,i + m₂ v _2,i

m ₁ + m₂

• 4.7 m/s to the west

• 4.8 m/s to the east

• 5.6 m/s to the north

• 3.8 m/s to the south

A 4.0 kg bowling ball sliding to the right at 8.0 m/s has an elastic head-on collision

with another 4.0 kg bowling ball initially at rest. The first ball stops after the

collision.

a. Find the velocity of the second ball after the collision.

v_2,f = m₁ v _1,i + m₂ v _2,i – m₁ v _1,f

m ₂

• 4.0 m/s to the left

• 8.0 m/s to the right

• 7.5 m/s to the right

• 9.0 m/s to the left

Two clay balls collide head-on in a perfectly

inelastic collision. The first ball has a mass of 0.500 kg and an initial

velocity of 4.00 m/s to the right. The second ball has a mass of

0.250 kg and an initial velocity of 3.00 m/s to the left. What is the

decrease in kinetic energy during the collision?

ΔKE = KE_f − KE_i

KEi = 1/2 m₁ v _1,i ² + 1/2 m₂ v_{,i 2} ²

KEf = 1/2 (m₁ + m₂) v _f ²

vf = m₁v_1,i + m₂v_2,i

m ₁ + m₂

• 4.07 J

• −4.07 J

• −6.12 J

• 8.14 J