Chapter 3 - Momentum and Force

Question 1

State the Law of Momentum

Answer 1

Always conserved if objects interact in a closed system (no external forces acting on them)

Question 2

When 2 objects push apart, they move…

Answer 2

• With different speeds (if unequal masses)

- With equal and opposite momentum –> total momentum = 0

Question 3

What does a force of an impact collision depend on?

Answer 3

Mass, direction and change in velocity

Question 4

What happens when you increase the impact time in a collision?

Answer 4

Lower impact force.

Question 5

What happens when you decrease the impact time in a collision?

Answer 5

Higher impact force

Question 6

What happens when 2 objects collide?

Answer 6

Exert equal and opposite forces on eachother. Momentum is unchanged.

Question 7

What happens to momentum in a front end impact?

Answer 7

Momentum is reduced

Question 8

What happens to momentum in a rear end impact?

Answer 8

Momentum is increased

Question 9

What do seat belts and airbags do to help protect you?

Answer 9

• Spread the impact force (over a bigger area)

- Increase impact time -> reduces overall force

Question 10

Apart from seat belts and airbags, what else can help protect you in a crash?

Answer 10

Crumple zones and side impact bars –> give way, increase impact times.
Also collapsible steering wheels

Question 11

How can you find the speed of an object before an impact?

Answer 11

Using the conservation of momentum