Linear Momentum
A system of particles is moving with a constant center-of-mass velocity. Which of the following statements must be true?
The net external force acting on the system is zero.
The kinetic energy of the system is constant.
The potential energy of the system is constant.
The individual velocities of all particles in the system are constant.
Two particles with masses and are moving along the x-axis. Particle 1 has a velocity of and particle 2 has a velocity of . What is the velocity of the center of mass of the system?
1.4 m/s
2.0 m/s
3.0 m/s
7.0 m/s
A 5 kg block is moving at 3 m/s on a frictionless surface when it collides head-on with a 2 kg block at rest. If the two blocks stick together after the collision, what is their final velocity?
1.43 m/s
2.14 m/s
2.86 m/s
3.00 m/s
A 2 kg ball moving at 5 m/s collides head-on with a 3 kg ball moving at -2 m/s. After the collision, the 2 kg ball moves at -1 m/s. What is the final velocity of the 3 kg ball?
2 m/s
3 m/s
4 m/s
5 m/s
A 1 kg ball moving at 10 m/s collides head-on with two stationary balls, each of mass 0.5 kg. After the collision, all three balls move separately along the same line. If the 1 kg ball stops completely, and one of the 0.5 kg balls moves at 4 m/s, what is the velocity of the other 0.5 kg ball?
6 m/s
12 m/s
16 m/s
20 m/s
A 2 kg object moving at 3 m/s in the positive x-direction collides with a 1 kg object moving at 4 m/s in the positive y-direction. If the two objects stick together after the collision, what is the magnitude of their final velocity?
2 m/s
3 m/s
4 m/s
5 m/s
A 1 kg ball moving at 5 m/s in the positive x-direction collides with a 1 kg ball at rest. After the collision, the first ball moves at 2 m/s at an angle of 30 degrees above the x-axis. What is the approximate speed of the second ball after the collision?
2.5 m/s
3.1 m/s
4.2 m/s
5.0 m/s

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A 0.5 kg ball strikes a wall with a velocity of 10 m/s and bounces back with a velocity of -8 m/s. What is the magnitude of the impulse on the ball?
1 Ns
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