Two objects of equal mass hit a wall with the same velocity. They both rebound with the same velocity. Both objects experience the same momentum change but one experiences twice the force as the other. Which of the following statements is true?
the contact time between the object and the wall of one is twice the contact time of the other
the contact time between the object and the wall of one is equal to the contact time of the other
the contact time between the object and the wall of one is one-half the contact time of the other
the change in the kinetic energy is the same for the two objects.
Two objects collide and stick together. Which of the following is false?
momentum is conserved
kinetic energy is lost
kinetic energy is conserved
momentum is lost
The Center of Mass of which of the following objects would not lie within the body itself?
Cricket Ball
Stone
Frisbee
Paperback book
If each mass in the figure is 1 kg, what is the x location of the center of mass?
0.50
0.67
1.00
1.33
An open box-car has a mass of 30,000 kg and is moving on a level railroad track at 4.00 m/s. 1,000 kg of water falls straight down into the box-car. The velocity of the box-car after the water falls into the box-car is
7.01 m/s.
6.55 m/s.
5.02 m/s.
3.87 m/s.
An astronaut in a space suit is motionless in outer space. The propulsion unit strapped to her back ejects some gas with a velocity of 50 m/s. The astronaut recoils with a velocity of 1.0 m/s. If the mass of the astronaut and space suit after the gas is ejected is 120 kg, the mass of the gas ejected is
1.0 kg.
1.9 kg.
2.4 kg.
3.00 kg.
A rocket with a mass of 500 grams is launched straight up. It achieves a velocity of 20.0 m/s in 2.00 seconds. The average thrust force of the engines on the rocket is
7.50 N.
9.90 N.
12.0 N.
13.5 N.
A rifle fires a bullet. Immediately after the bullet is fired, which of the following is NOT true?
the rifle and the bullet have the same magnitude of momentum
the force on the rifle due to the bullet and the force on the bullet due to the rifle have the same magnitude
the rifle and the bullet do not have the same kinetic energy
the rifle and the bullet have the same kinetic energy
A 90 kg person is sitting in a boat at rest with a mass of 100 kg. In the boat is a stone with a mass of 5.0 kg. The person throws the stone at 4.00 m/s horizontally in the NORTH direction. The velocity of the person and the boat after the throwing the stone is
2.00 m/s NORTH
1.21 m/s SOUTH.
1.21 m/s NORTH.
0.11 m/s SOUTH.
A 4.00 kg ball is traveling at 5.00 m/s and strikes a wall. The 4.00 kg ball bounces off the wall with a velocity of 4.0 m/s. The change in momentum of the ball is
8.0 kg m/s.
13 kg m/s.
26 kg m/s
36 kg m/s.
A 4.00 kg ball is moving at 2.00 m/s to the WEST and a 6.00 kg ball is moving at 2.00 m/s to the NORTH. The total momentum of the system is
21.6 kg m/s at an angle of 17.7 degrees NORTH of WEST.
14.4 kg m/s at an angle of 45.2 degrees SOUTH of WEST.
21.6 kg m/s at an angle of 45.2 degrees SOUTH of WEST.
14.4 kg m/s at an angle of 56.3 degrees NORTH of WEST.
A 30.0 kg mass falls from a height of 4.0 m. The momentum of the mass just before it hits the ground is
144.2 kg m/s
187.8 kg m/s.
320.0 kg m/s.
442.4 kg m/s.
A 3.000 kg ball is pitched with a kinetic energy of 20.00 Joules. Then the momentum of the ball is
7.500 kg m/s.
8.350 kg m/s.
9.450 kg m/s.
10.95 kg m/s.
A 3.0 kg object is moving to the right at 4.0 m/s. It collides in a perfectly inelastic collision with a 6.0 kg object moving to the left at 2.0 m/s. What is the total kinetic energy after the collision?
62 J
25 J
12 J
0.0 J
A 140 gm baseball with a velocity of 25.0 m/s is hit by a baseball bat and leaves at 30.0 m/s in the opposite direction. If the ball was in contact with the bat for 12.0 ms, what is the average force on the ball?
750 N
642 N
550 N
482 N
A 1200 kg car travels at 25.0 m/s and collides head-on in a perfectly inelastic collision with a stationary 2400 kg truck. The kinetic energy lost in the collision is
330,000 J
250,000 J.
125,000 J.
95,000 J.
A 1200 kg car is moving at 5.0 m/s EAST. It strikes an 1800 kg car at rest. The cars have an elastic collision and move in the EAST or WEST direction. The velocity of the 1800 kg car after the collision is
3.0 m/s WEST
1.0 m/s EAST
4.0 m/s EAST
4.0 m/s WEST
A 100 kg mass is blown apart into a 90.0 kg piece and a 10.0 kg piece. After the blast, the two masses are moving apart with a relative velocity of 100 m/s. The velocity of the 10.0 kg mass after the explosion is 90.0 m/s. The total kinetic energy of the two masses after the explosion is
63,200 J.
45,000 J.
30,400 J.
23,400 J.
take it the reverse way.. like two mases colliding to form one mass and after collision the complete mass is at rest. so
m1v1+m2v2/m1+m2=0
solve for v2 and substitue it in the next equation u will get the answer
A 3.000 kg ball is pitched with a kinetic energy of 20.00 Joules. Then the momentum of the ball is
5.48 kg m/s
8.35 kg m/s
10.95 kg m/s
9.45 kg m/s
If the momentum of a ball is doubled, then the kinetic energy is
0.5 times larger.
2 times larger.
3 times larger.
4 times larger.