3.3 Dynamics

Question 1

3.3.1 State the principle of conservation of momentum:

Answer 1

The total momentum of a system remains constant provided no external force acts on the system.

Question 2

3.3.2 For an elastic collision (list properties) …

Answer 2

• Total kinetic energy is conserved.
• The relative speed of approach is equal to the relative speed of separation.

Question 3

3.3.3 What is always conserved in a closed system in an interaction of two objects?

Answer 3

Momentum is always conserved in a closed system.
Total momentum before a collision = Total momentum after a collision.

Question 4

3.3.3 What can change even if the momentum is conserved, and in what case?

Answer 4

Sometimes, the total kinetic energy is not conserved such as in inelastic collisions.

Question 5

If two objects coalesce after a collision, what kind of collision was it?

Answer 5

An inelastic collision, because it means that there was some kinetic energy lost in the collision.