Download Assignment 9 (365178)

Assignment 9 (365178)
In a ballistics test, a 25 g bullet traveling horizontally at 1200 m/s goes through a
25 cm thick 350 kg stationary target and emerges with a speed of 900 m/s. The
target is free to slide on a smooth horizontal surface.
(a) How long is the bullet in the target?
s
What average force does it exert on the target?
N (magnitude only)
(b) What is the target's speed just after the bullet emerges?
m/s
A 100 g ball is dropped from a height of 3.2 m, bounces on a hard floor, and
rebounds to a height of 2.4 m. Figure P9.28 shows the impulse received from the
floor. What maximum force does the floor exert on the ball?
N
Figure P9.28
Far in space, where gravity is negligible, a 410 kg rocket traveling at 75 m/s fires
its engines. Figure P9.26 shows the thrust force as a function of time, with the
horizontal axis in 12 s increments. The mass lost by the rocket during these 36 s
is negligible.
Figure P9.26
(a) What impulse does the engine impart to the rocket?
N s
(b) At what time does the rocket reach its maximum speed?
s
What is the maximum speed?
m/s
A 750 g air-track glider collides with a spring at one end of the track. Figure
Ex9.11 shows the glider's velocity and the force exerted on the glider by the
spring. How long is the glider in contact with the spring?
s
Figure Ex9.11
(a) A 1.5 kg object is moving to the right with a speed of 0.7 m/s when it
experiences the force shown in Figure Ex9.7a (below). What are the object's
speed and direction after the force ends?
---Select---
m/s
(b) Answer this question for the force shown in Figure Ex9.7b.
m/s
---Select---
Figure Ex9.7
What value of Fmax gives an impulse of 6.4 Ns?
N
Figure Ex9.3
A sled slides along a horizontal surface on which the coefficient of kinetic friction
is 0.20. Its velocity at point A is 7.8 m/s and at point B is 4.2 m/s. Use the
impulse-momentum theorem to find how long the sled takes to travel from A to B.
s
A 7,000 kg railroad car is rolling at 3.5 m/s when a 4000 kg load of gravel is
suddenly dropped in. What is the car's speed just after the gravel is loaded?
m/s
A 1000 kg cart is rolling to the right at 3.5 m/s. A 90 kg man is standing on the
right end of the cart. What is the speed of the cart if the man suddenly starts
running to the left with a speed of 10 m/s relative to the cart?
m/s