Physics Quiz 4

What is the principle behind conservation of mechanical energy?

• Mechanical energy is only conserved in certain situations

• The total mechanical energy of a system remains constant if no external forces are acting on it.

• Mechanical energy can be created or destroyed

• Mechanical energy only applies to moving objects

What is the equation for calculating impulse?

• Impulse = Distance / Time

• Impulse = Power * Time

• Impulse = Mass * Velocity

• Impulse = Force * Time

What is the equation for momentum?

• momentum (p) = mass + velocity

• momentum (p) = mass * velocity

• momentum (p) = mass / velocity

• momentum (p) = mass - velocity

Define perfectly inelastic collisions.

• Two objects stick together after colliding and move as a single unit with a common velocity.

• Two objects collide and come to a complete stop.

• Two objects bounce off each other and move in opposite directions.

• Two objects collide and continue moving with different velocities.

In a perfectly inelastic collision, what happens to the kinetic energy of the system?

• The kinetic energy of the system increases.

• The kinetic energy of the system is not conserved.

• The kinetic energy of the system decreases.

• The kinetic energy of the system remains the same.

What are elastic collisions?

• Collisions where both momentum and kinetic energy are conserved.

• Collisions where neither momentum nor kinetic energy are conserved.

• Collisions where only kinetic energy is conserved.

• Collisions where only momentum is conserved.

What is the difference between inelastic and elastic collisions?

• In an inelastic collision, kinetic energy is NOT conserved and the objects stick together after the collision. In an elastic collision, kinetic energy IS conserved and the objects bounce off each other after the collision.

• In an inelastic collision, kinetic energy IS conserved and the objects stick together after the collision. In an elastic collision, kinetic energy is NOT conserved and the objects bounce off each other after the collision.

Select all the examples of a collision

• Two cars colliding head-on on a highway.

• car driving at top speed

• car at a stop light

• baseball bat hitting a ball

A 2200kg car travelling at 30m/s collides with another 2200kg car that is at rest. The two bumpers lock and he cars move forward together. What is their final velocity?

• 60 m/s

• 30 m/s

• 0 m/s

• 15 m/s

A 10kg ball moving at 13 m/s strikes a 20kg ball at rest. After the collision the 10kg ball is moving with a velocity of 7 m/s. What is the velocity of the second ball?

• 20 m/s
• 10 m/s
• 0 m/s
• 3 m/s