Collisions and Conservation Principles

The lecture introduces the concept of momentum conservation in isolated systems, where net forces are zero, ensuring constant momentum. It covers elastic collisions, where both momentum and kinetic energy are conserved, and inelastic collisions, where kinetic energy is not conserved, often resulting in objects sticking together. Examples illustrate these concepts, including calculations of velocities and energy changes. The lecture concludes with a summary of key points, emphasizing the conservation of momentum and the differences between elastic and inelastic collisions.

What is conserved in an isolated system according to the conservation of momentum?

• Temperature

• Momentum

• Mass

• Kinetic Energy

In an elastic collision, what happens to the kinetic energy?

• It is converted to potential energy

• It is conserved

• It is doubled

• It is lost

During an elastic collision, if the initial velocity of an object is 4 m/s, what can be said about its final velocity?

• It will be negative

• It will be different

• It will be zero

• It will be the same

What is a characteristic of inelastic collisions?

• Objects bounce off each other

• Kinetic energy is conserved

• Momentum is not conserved

• Objects stick together

In the example of a hockey player catching a puck, what type of collision is demonstrated?

• Elastic

• Gravitational

• Inelastic

• Perfectly elastic

When two objects stick together after a collision, what can be said about their velocities?

• One is at rest

• They have different velocities

• They move in opposite directions

• They have the same velocity

How is the recoil velocity calculated in an inelastic collision?

• By using the conservation of momentum

• By subtracting the velocities

• By adding the masses

• By dividing the kinetic energies

What happens to kinetic energy in an inelastic collision?

• It is increased

• It is unchanged

• It is lost

• It is conserved

In the hockey example, how much kinetic energy was lost in the collision?

• 0.196 joules

• 91.9 joules

• 91.7 joules

• 35 joules

Where does the lost kinetic energy go in an inelastic collision?

• It is converted to sound and heat

• It disappears

• It is stored as potential energy

• It remains as kinetic energy