Physics 011

MC#7A

Chapter 7 : Linear Momentum

1.	How fast must a 2000-kg body travel in order to have the same momentum as a 200-g body traveling at 200 m/s? Your answer: 0.02 m/s
2.	A target rifle is held horizontally at rest and fired. The bullet with mass mo leaves the barrel of the gun with speed vo, linear momentum of magnitude po and kinetic energy KEo. The gun has mass Mo (>>mo). The recoil speed of the rifle is ___ vo. The correct answer: less than See Section 7-2
3.	A target rifle is held horizontally at rest and fired. The bullet with mass mo leaves the barrel of the gun with speed vo, linear momentum of magnitude po and kinetic energy KEo. The gun has mass Mo (>>mo). The magnitude of the linear momentum of the recoiling rifle is ___ po. The correct answer: equal to See Section 7-2
4.	A target rifle is held horizontally at rest and fired. The bullet with mass mo leaves the barrel of the gun with speed vo, linear momentum of magnitude po and kinetic energy KEo. The gun has mass Mo (>>mo). The kinetic energy of the recoiling rifle is ___ KEo. Your answer: much less than
5.	A target rifle is held horizontally at rest and fired. The bullet with mass mo leaves the barrel of the gun with speed vo, linear momentum of magnitude po and kinetic energy KEo. The gun has mass Mo (>>mo). If the mass of the bullet had been slightly smaller, the magnitude of the sum of the linear momentum of the bullet and the linear momentum of the gun would have been ___. The correct answer: the same See Section 7-2
6.	A rifle with a mass of 0.20 kg fires a 0.50-gram bullet with an initial velocity of 100 m/s. What is the recoil velocity of the rifle? Your answer: 0.25 m/s
7.	A 0.2-kg ball is bounced against a wall. It hits the wall with a speed of 20 m/s and rebounds elastically. What is the magnitude of the change in momentum of the ball? The correct answer: 8 kg m/s See Sections 7-1, 3-3
8.	A 30-kg cart traveling due north at 5 m/s collides with a 50-kg cart that had been traveling due south. Both carts immediately come to rest after the collision. What must have been the speed of the southbound cart? Your answer: 3 m/s
9.	A red object with mass 3 mo moves with a speed of 3 vo toward the north. A blue object with mass 2 mo moves with speed 6vo toward the south. A perfectly inelastic collision occurs in which the two objects stick together and move as one object after the collision. The total kinetic energy of the two objects just after the collision is ___ the total kinetic energy of the two objects just before the collision. The correct answer: less than See Section 7-6
10.	A red object with mass 3 mo moves with a speed of 3 vo toward the north. A blue object with mass 2 mo moves with speed 6vo toward the south. A perfectly inelastic collision occurs in which the two objects stick together and move as one object after the collision. The magnitude of the sum of the linear momentum of the two objects just after the collision is ___ the magnitude of the sum of the linear momentum of the two objects just before the collision. The correct answer: equal to See Section 7-2
11.	A red object with mass 3 mo moves with a speed of 3 vo toward the north. A blue object with mass 2 mo moves with speed 6vo toward the south. A perfectly inelastic collision occurs in which the two objects stick together and move as one object after the collision. The magnitude of the total linear momentum of the two objects just before the collision is movo x ___. The correct answer: 3 See Section 7-2
12.	A red object with mass 3 mo moves with a speed of 3 vo toward the north. A blue object with mass 2 mo moves with speed 6vo toward the south. A perfectly inelastic collision occurs in which the two objects stick together and move as one object after the collision. If the speed of the red object had been slightly more, the magnitude of the total linear momentum of the two objects would have been ___. Your answer: less
13.	A red object with mass 3 mo moves with a speed of 3 vo toward the north. A blue object with mass 2 mo moves with speed 6vo toward the south. A perfectly inelastic collision occurs in which the two objects stick together and move as one object after the collision. Immediately after the collision, the two objects will ___. The correct answer: move toward the south See Section 7-2
14.	A car with a mass of 800 kg is stalled on a road. A truck with a mass of 1200 kg comes around the curve at 20 m/s and hits the car. The two vehicles remain locked together after the collision. What is their speed after the impact? The correct answer: 12 m/s See Section 7-6
15.	A 1000 kg car traveling at 5.0 m/s overtakes and collides with a 3000 kg truck travelling in the same direction at 1.0 m/s. During the collision the two vehicles couple together and continue to move as one unit. What is the speed of the coupled vehicles? The correct answer: 2.0 m/s See Section 7-6
16.	A tennis ball is hit with a tennis racket and the change in the momentum of the ball is 4 kg m/s. If the collision time of the ball and racket is 0.01 seconds, what is the magnitude of the force exerted by the ball on the racket? Your answer: 400 N
17.	A 160-pound jogger runs at a constant speed. What is his momentum if he covers 100 yards in 10 seconds? The correct answer: 150 slug ft /s See Section 7-1
18.	A spacecraft with a total mass of 10,000 kg lifts off from the Kennedy Space Center in Florida. Its rockets burn for 15 seconds and produce a thrust of 3.0 x 10^5 N. Assuming that the net mass of the spaceship does not change as the rocket fuel is consumed, what is the final velocity of the spaceship? The correct answer: 4.5 x 10^2 m/s See Section 7-3
19.	In a combustion engine, gas is burned. The resulting explosion produces a force that drives the pistons in the engine. The force of the explosion on the piston is due to the change in momentum of the gas molecules. A 0.4-g sample of gas produces a force of 2400 N in an explosion that lasts 10^-3 seconds. What must be the speed of the gas molecules? The correct answer: 3 x 10^3 m/s See Section 7-3
20.	A bomb of mass 4 mo initially at rest explodes into two pieces. One piece with a mass 3 mo moves toward the east with speed vo and kinetic energy KEo. The speed of the second bomb fragment will be vo x ___. The correct answer: 3 See Section 7-2
21.	A bomb of mass 4 mo initially at rest explodes into two pieces. One piece with a mass 3 mo moves toward the east with speed vo and kinetic energy KEo. The kinetic energy of the second bomb fragment is ___ KEo. The correct answer: more than See Sections 7-2, 6-3
22.	A second bomb with more powder than the first one also initially at rest explodes into two pieces. The masses of these two pieces are the same as for the first bomb. The magnitude of the total linear momentum of the two bomb fragments for this second bomb is ___ the magnitude of the total linear momentum of the bomb fragments in the first explosion. The correct answer: equal to See Section 7-2