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. a Sketch a velocity–time graph for the phone from when it leaves the girl's hand to when it hits the ground.
b. b Calculate the time it takes for the phone to hit the ground.
c. c Calculate the phone's velocity just before it hits the ground.