Chapter 9 Motion Equations and revision notes

Question 1

9.1 Speed, v (metres per second, m/s) equation

Answer 1

distance travelled, s (metres,m) / time taken, t (seconds, s)

Question 2

9.2 Acceleration, a (metres per second, m/s^2) equation

Answer 2

Change in velocity (m/s) / time taken for the change (s)

Question 3

9.2 Change of velocity equation

Answer 3

Final velocity - initial velocity

Question 4

9.3 What does the gradient of a velocity-time graph represent

Answer 4

It represents the acceleration

Question 5

9.4 What does the tangent of a velocity-time graph represent?

Answer 5

This finds the acceleration of the graph

Question 6

9.1 If an object is moving at a constant speed, what does a distance time-graph show?

Answer 6

It will have a straight line sideways

Question 7

9.2 What is decelration?

Answer 7

A negative acceleration when an object slows down.

Question 8

9.2 Why does an object’s velocity change when it goes in a circle even though it has the same speed.

Answer 8

It is because the direction keeps changing (velocity is a vector quantity).

Question 9

9.2 What is a displacement?

Answer 9

It is a straight line from the start to the finish.

Question 10

9.1 When an object is stationary, how is this represented on a distance-time graph?

Answer 10

Stationary, is a horizontal line

Question 11

9.1 What does the gradient of a distance-time graph for an object represent?

Answer 11

It represents the object’s speed

Question 12

9.2 What is a vector quantity?

Answer 12

It is a physical quantity that has a direction as well as a magnitude.

Question 13

9.2 What is a scalar quantity?

Answer 13

A scalar quantity is a physical quantity that has a magnitude only and does not have a direction.

Question 14

9.3 How can you measure velocity changes?

Answer 14

A motion sensor linked to a computer can be used to measure velocity changes.

Question 15

9.3 What does the gradient in a velocity-time graph show?

Answer 15

It represents the accelaration

Question 16

9.3 If a velocity-time graph is a horizontal line, what happens to the acceleration?

Answer 16

The acceleration is zero

Question 17

9.3 What does a positive gradient and a negative gradient represent in a velocity-time graph?

Answer 17

A positive gradient represents positive acceleration

A negative gradient represents decelaration

Question 18

9.3 What does the area under the graph in a velocity-time graph represent?

Answer 18

The area under the line on a velocity-time graph represents distance travelled

Question 19

9.4 How is the speed of an object moving at a constant speed represented on a distance-time graph?

Answer 19

It is given by the gradient of the line on its distance-time graph