P3 interim A extras

Question 1

Describe the motion in this speed time graph.

Answer 1

From A to B, constant speed. From B to C, stationary.

From C to D, accelerating.

From D to E, stationary.

From E to F constant speed towards start point.

Question 2

Calculate the speed from this distance time graph.

Answer 2

It’s the gradient of the graph so, 70m/10s = 7m/s

Question 3

Describe the motion in this speed time graph.

Answer 3

From 0 to A, accelerating. From A to B, constant speed, from B to C, decelerating.

Question 4

Calulate the acceleration between 0 and A.

Answer 4

Acceleration is the gradient so, 10m/s divided by 5s = 2m/s2

Question 5

Calculate the acceleration of the car.

Answer 5

Force = mass x acceleration so, a = F/m which gives 2000N/250 kg = 8m/s2

Question 6

What effect does doubling the speed have on thinking and braking distances?

Answer 6

The thinking distance is doubled, but the braking distance is quadrupled.

Question 7

Rearrange K.E. = 1/2 mv² to give

m =

Answer 7

You should get:

m = 2 K.E./v²

Question 8

Why is the thinking distance line straight, but the braking distance line is curved?

Answer 8

Braking distance depends on kinetic energy which has speed2 in the equation.