A girl drops her mobile phone from a window that is 15 m above the ground. Taking the acceleration of the Earth's gravitational field to be 10 ms−2 and ignoring any effects of air friction:
(a) Sketch a velocity–time graph for the phone from when it leaves the girl's hand to when it hits the ground.
(b) Calculate the time it takes for the phone to hit the ground.
(c) Calculate the phone's velocity just before it hits the ground.