1) Two blocks of masses m1 and m2 are released from the top of two frictionless
ID: 1697077 • Letter: 1
Question
1) Two blocks of masses m1 and m2 are released from the top of two frictionless inclined planes of the same height making 30 and 60 degree angles with the horizontal direction. Which of the blocks is going faster when it reaches the bottom of its respective incline?a) we must know the actual masses of the blocks to answer
b) both blocks have the same speed at the bottom
c) block 1 is faster
d) block 2 is faster
e) there is not enough information to answer the question
2) Jacques and George meet in the middle of a lake while paddling in their canoes. They come to a complete stop and talk for a while. When they are ready to leave, Jacques pushes George's canoe with a force F to separate the two canoes. What is correct to say about the final momentum and kinetic energy of the system?
a) the final momentum is in the direction of F but the final kinetic energy is zero J
b) the final momentum is in the direction opposite of F but the final kinetic
energy is zero
c) The final momentum is in the direction of F and the final kinetic energy
is positive
d) The final momentum is zero kg* m/s and the final kinetic energy is zero J
e) The final momentum is zero kg *m/s but the final kinetic energy is positive
3) In an elastic collistion, mass m2 is at rest and mass m1 hits it with velocity v. If m1 is less than m2, in what direction will m1 be moving after the collision?
a) It will come to a stop
b) it will continue moving in the same direction
c) it will be moving in the opposite direction from which it approached
d) it is not possible to say without knowing more about the masses
4) A 14,000 kg boxcar is coasting at 1.50 m/s along a horizontal track when it hits and attaches to a stationary 10,000 kg boxcar. What is the speed of the cars after the collision?
5) Two masses are connected by a string, which goes over an ideal pulley. Block A has a mass of 3 kg and can slide along a rough plane inclined 30 degrees to the horizontal. The coefficient of static friction between block A and the plane is 0.4. What mass should block B have in order to start block A sliding up the ramp?
Explanation / Answer
1) Two blocks of masses m1 and m2 are released from the top of two frictionless inclined planes of the same height making 30 and 60 degree angles with the horizontal direction. Which of the blocks is going faster when it reaches the bottom of its respective incline? d) block 2 is faster 2) Jacques and George meet in the middle of a lake while paddling in their canoes. They come to a complete stop and talk for a while. When they are ready to leave, Jacques pushes George's canoe with a force F to separate the two canoes. What is correct to say about the final momentum and kinetic energy of the system? e) The final momentum is zero kg *m/s but the final kinetic energy is positive 3) In an elastic collistion, mass m2 is at rest and mass m1 hits it with velocity v. If m1 is less than m2, in what direction will m1 be moving after the collision? c) it will be moving in the opposite direction from which it approached 4) A 14,000 kg boxcar is coasting at 1.50 m/s along a horizontal track when it hits and attaches to a stationary 10,000 kg boxcar. What is the speed of the cars after the collision? 14000*1.5/(14000+10000)=0.875(m/s) 5) Two masses are connected by a string, which goes over an ideal pulley. Block A has a mass of 3 kg and can slide along a rough plane inclined 30 degrees to the horizontal. The coefficient of static friction between block A and the plane is 0.4. What mass should block B have in order to start block A sliding up the ramp? Friction force acts on block A. ma*g*cos(30)*0.4=10.2(N). so T=10.2+ma*g*sin(30)=24.9(N). so mb=24.9/9.8=2.54(kg)
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