Question

# 1. (a) Calculate the momentum of a 2100 kg elephant charging a hunter at a speed of 7.50

m/s.

kg·m/s

(b) Compare the elephant's momentum with that of a 0.0400 kg bullet fired at a speed of 600 m/s.

(momentum of elephant / momentum of bullet)

(c) What is the momentum of the 90.0 kg hunter running at 7.50 m/s after missing the elephant?

kg·m/s

2. One hazard of space travel is debris left by previous missions. There are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. Calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 10^{3} m/s and sticks, given the collision lasts 6.00 ✕ 10^{-8} s. Such a collision chipped the window of the ill-fated Challenger in June 1983, causing $50,000 of damage.

N

3. A 0.950 kg hammer is moving horizontally at 7.50 m/s when it strikes a nail and comes to rest after driving it 1.00 cm into a board.

(a) Calculate the duration of the impact.

s

(b) What was the average force exerted on the nail?

N

4. Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of 180,000 kg and a velocity of 0.300 m/s, and the second having a mass of 125,000 kg and a velocity of -0.120 m/s. (The minus indicates direction of motion.) What is their final velocity?

m/s

5. Two manned satellites approaching one another at a relative speed of 0.250 m/s intend to dock. The first has a mass of 4.50 ✕ 10^{3} kg, and the second a mass of 7.50 ✕ 10^{3} kg. If the two satellites collide elastically rather than dock, what is their final relative velocity? Adopt the reference frame in which the second satellite is initially at rest and assume that the positive direction is directed from the second satellite towards the first satellite.

m/s

6. A 0.0260 kg bullet moving horizontally at 500 m/s embeds itself into an initially stationary 0.500 kg block.

(a) What is their velocity just after the collision?

m/s

(b) The bullet-embedded block slides 8.0 m on a horizontal surface with a 0.30 kinetic coefficient of friction. Now what is its velocity?

m/s

(c) The bullet-embedded block now strikes and sticks to a stationary 2.00 kg block. How far does this combination travel before stopping?

m

7. Two manned satellites approaching one another at a relative speed of 0.500 m/s intend to dock. The first has a mass of 2.00 ✕ 10^{3} kg, and the second a mass of 7.50 ✕ 10^{3} kg. Assume that the positive direction is directed from the second satellite towards the first satellite.

(a) Calculate the final velocity after docking, in the frame of reference in which the first satellite was originally at rest.

m/s

(b) What is the loss of kinetic energy in this inelastic collision?

J

(c) Repeat both parts, in the frame of reference in which the second satellite was originally at rest.

final velocity

m/s

loss of kinetic energy

J

8. Two cars collide at an icy intersection and stick together afterward. The first car has a mass of 1650 kg and was approaching at 8.00 m/s due south. The second car has a mass of 700 kg and was approaching at 18.0 m/s due west.

(a) Calculate the final velocity of the cars. (Note that since both cars have an initial velocity, you cannot use the equations for conservation of momentum along the *x*-axis and *y*-axis; instead, you must look for other simplifying aspects..)

Magnitude

m/s

Direction

Â° (counterclockwise from west is positive)

(b) How much kinetic energy is lost in the collision? (This energy goes into deformation of the cars.)

J