Exam 9: Linear Momentum

Two objects are moving in the xy-plane. Object A has a mass of 3.2 kg and has a velocity = (2.3 m/s) + (4.2 m/s) and object B has a mass of 2.9 kg and has a velocity = (-1.8 m/s) + (2.7 m/s) . What is the total momentum of the system?

The center of mass of an object has to be located within the object.

Collisions in which kinetic energy is conserved are said to be ineleatic collisions.

A golf club exerts an average force of 1000 N on a 0.045-kg golf ball which is initially at rest. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball as it leaves the tee?

State the Law of Conservation of Linear Momentum.

A 10.0-kg mass is located at (2.00 m) + (3.00 m) . A 15.0-kg mass is located at (4.00 m) . A 25-kg mass is located at (2.00 m) . What is the location of the center of mass of this system?

When a ball undergoes a one-dimensional elastic collision with a wall, the velocity of the ball is reversed, while the wall remains stationary. Explain why this does not violate conservation of momentum.

In an inelastic collision, the total kinetic energy after the interaction can be greater than the initial kinetic energy.

The center of mass of a system of particles (or objects) with total mass M moves like a single particle of mass M acted upon by the same net external force.

A firecracker breaks up into two pieces, one has a mass of 200 g and flies off along the x-axis with a speed of 82.0 m/s and the second has a mass of 300 g and flies off along the y-axis with a speed of 45.0 m/s. What is the total momentum of the two pieces?

State Newton's second law of motion in terms of momentum.

Define an inelastic collision in terms of conservation of momentum and energy.

In a one-dimensional elastic collision of two identical masses, the masses always exchange velocities.

In any elastic head-on collision, the relative speed of the two objects after the collision has the same magnitude (but opposite direction) as before the collision, no matter what the masses are.

A 620-g object traveling at 2.1 m/s collides head-on with a 320-g object traveling in the opposite direction at 3.8 m/s. If the collision is perfectly elastic, what is the change in the kinetic energy of the 620-g object?

A 4.00-kg mass and a 9.00-kg mass are being held at rest against a compressed spring on a frictionless surface. When the masses are released, the 4.00-kg mass moves to the east with a speed of 2.00 m/s. What is the velocity of the 9.00-kg mass after the masses are released?

A 1000-kg helicopter hovers over a forest fire and starts to squirt water downward with a speed of 10 m/s at a rate of 40 kg/s. What is the initial upward acceleration on the helicopter when it first starts to release the water?

A plate falls vertically to the floor and breaks up into three pieces, which slide along the floor. Immediately after the impact, a 200-g piece moves along the x-axis with a speed of 2.00 m/s and a 235-g piece moves along the y-axis with a speed of 1.50 m/s. The third piece has a mass of 100 g. In what direction does the third piece move?

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 to separate the two canoes. What is correct to say about the final momentum and kinetic energy of the system?

Two objects are moving in the xy-plane. Object A has a mass of 3.5 kg and has a velocity of 5.3 m/s at an angle of 30° from the x-axis and object B has a mass of 1.9 kg and has a velocity of 6.2 m/s at an angle of 72° from the x-axis. What is the total momentum of the system?