Changing speed

Question 1

Describe the trends in speed and time from a simple

speed-time graph:

Answer 1

• horizontal line – constant speed
• straight line positive gradient – increasing speed
• straight line negative gradient – decreasing
speed.

Question 2

Recognise that acceleration involves a change in

speed (limited to motion in a straight line):

Answer 2

• speeding up involves an acceleration
• slowing down involves a deceleration
• greater change in speed (in a given time) results
in higher acceleration.

Question 3

what is acceleration measured in?

Answer 3

metres per second squared (m/s2)

Question 4

equation for acceleration

Answer 4

acceleration = change in speed / time taken

Question 5

what factor is important when describing

the motion of an object?

Answer 5

direction

Question 6

what is the velocity of an object?

Answer 6

its speed combined with its direction

Question 7

Describe graphs of speed against time for uniform acceleration

Answer 7

• greater acceleration shown by a higher gradient
• the significance of a positive or negative gradient
• calculations of distance traveled from a simple
speed-time graph for uniform acceleration.

Question 8

Describe acceleration as change in speed per unit

time and that:

Answer 8

• increase in speed results from a positive
acceleration
• decrease in speed results from a negative
acceleration or deceleration.

Question 9

what does it mean if two objects moving in opposite

directions at the same speed?

Answer 9

their velocities will have identical magnitude but opposite signs.

Question 10

Calculate the relative velocity of objects moving in

parallel.

Answer 10

Relative velocity = velocity 1 - velocity 2

Question 11

what does acceleration involve a change in?

Answer 11

• in speed
• in direction
• in both speed and direction.