Topic Menu

Cyber-chess a chess instruction site

Equations of Motion

Q1.

(a) Indicate with a tick in the correct box which of the following

quantities are vectors and which are scalars.

  velocity speed distance displacement
scalar        
vector        

[2 marks]

(b) A tennis ball is thrown vertically downwards and bounces on the ground. The ball leaves the hand with an initial speed of 1.5 m s–1 at a height of 0.65 m above the ground. The ball rebounds and is caught when travelling upwards with a speed of 1.0 m s–1. Assume that air resistance is negligible.

(i) Show that the speed of the ball is about 4 m s–1 just before it strikes the ground.

[3 marks]

(ii) The ball is released at time t = 0. It hits the ground at time tA and is caught at time tB. On the axes provided, sketch a velocity–time graph for the vertical motion of the tennis ball from when it leaves the hand to when it returns.

The initial velocity X and final velocity Y are marked on the graph for you.

[3 marks]

(c) In a game of tennis, a ball is hit horizontally at a height of 1.2 m and travels a horizontal distance of 5.0 m before reaching the ground.

The ball is at rest when hit.

Calculate the initial horizontal velocity given to the ball when it was hit.

[3 marks]

(Total 11 marks)