Changes In Momentum

Question 1

What causes a change in momentum?

Answer 1

A resultant force acting on an object for a certain amount of time

This relates to Newton’s 2nd Law.

Question 2

According to Newton’s 2nd Law, how is force defined?

Answer 2

Force = mass × change in velocity

This implies that acceleration is a change in velocity over time.

Question 3

What is the formula for change in momentum?

Answer 3

Change in momentum (kg m/s) = mv - mu

Where ‘m’ is mass and ‘v’ and ‘u’ are final and initial velocities respectively.

Question 4

What happens to the forces on the body during a quick change in momentum?

Answer 4

The forces on the body will be very large, increasing the likelihood of injury

This is particularly relevant in situations like car crashes.

Question 5

What does conservation of momentum demonstrate in relation to Newton’s Third Law?

Answer 5

It shows that reaction forces are equal and opposite

This is illustrated through the example of colliding snooker balls.

Question 6

What is the total momentum of a system before a collision involving a white ball (0.15 kg) with a momentum of 0.6 kg m/s?

Answer 6

0.6 kg m/s

The red ball has a momentum of zero before the collision.

Question 7

What occurs to the momentum of the white and red balls after a collision if the white ball continues at 1 m/s and the red ball begins moving at 3 m/s?

Answer 7

The total momentum remains 0.6 kg m/s

This illustrates the principle of conservation of momentum.

Question 8

How can the force that caused a change in velocity for each ball be calculated?

Answer 8

F = (mv - mu) / t

This applies to both the white and red balls.

Question 9

What is the stopping distance of a vehicle dependent on?

Answer 9

• Your reaction time
• Your speed
• The mass of the vehicle
• The condition of the road
• The friction present on the road

These factors all contribute to how quickly a vehicle can stop.

Question 10

What are the two components of stopping distance?

Answer 10

• Thinking distance
• Braking distance

Thinking distance is influenced by reaction time and speed, while braking distance is influenced by speed, mass, road condition, and friction.

Question 11

Fill in the blank: The longer it takes to stop a car, the longer the _______.

Answer 11

stopping distance

Question 12

What is one method to measure reaction time?

Answer 12

Using a ruler drop test

This involves a person catching a ruler dropped from a height.

Question 13

True or False: Bad visibility can affect stopping distance.

Answer 13

True

Poor visibility can increase reaction times, affecting overall stopping distance.