P9 Motion

Question 1

What does the gradient of a line on distance-time graph represent?

Answer 1

Speed

Question 2

State the equation linking distance, speed and time

Answer 2

distance = speed x time
distance (m), speed (m/s), time (s)

Question 3

How to calculate speed for an object moving at constant speed

Answer 3

speed = distance / time
speed (m/s), distance (m), time (s)

Question 4

Why can an object travelling at a constant speed in a circle not have a constant velocity?

Answer 4

• Speed is a scalar quantity
• Velocity is a vector quantity which means it can only be constant if the direction is constant
• In circular motion, the direction is constantly changing
• So its velocity is not constant even if its speed is constant

Question 5

How to calculate acceleration

Answer 5

acceleration = change in velocity / time taken for change
acceleration (m/s²), change in velocity (m/s), time (s)

Question 6

What is velocity?

Answer 6

Speed in a given direction

Question 7

How can distance travelled by an object be calculated from a velocity-time graph?

Answer 7

Distance travelled is equal to the area under the graph

Question 8

What is acceleration?

Answer 8

The rate of change of velocity

Question 9

What is deceleration?

Answer 9

The change of velocity per second when an object slows down

Question 10

How can acceleration of an object be calculated from a velocity-time graph?

Answer 10

Acceleration is equal to the gradient of the line