6. Anila is practising catching tennis balls. She uses a mobile computer-controlled machine which fires tennis balls vertically upwards from a height of 2.5 metres above the ground. Once it has fired a ball, the machine is programmed to move position rapidly to allow Anila time to get into a suitable position to catch the ball. The machine fires a ball at \(24 \mathrm {~ms} ^ { - 1 }\) vertically upwards and Anila catches the ball just before it touches the ground.

1. Draw a speed-time graph for the motion of the ball from the time it is fired by the machine to the instant before Anila catches it.
2. Find, to the nearest centimetre, the maximum height which the ball reaches above the ground.
3. Calculate the speed at which the ball is travelling when Anila catches it.
4. Calculate the length of time that the ball is in the air.