Sketch the graphs to show how the horizontal and vertical components of the velocity of the ball, and change with time t just before the ball hits the ground.
Sketch the graph to show how the displacement s of the stone changes with time t from when it is thrown in the air to when it touches the surface of the sea.
A third particle now falls under the effect of both gravity and air resistance.
After falling for some time, its resultant force becomes zero for the rest of its motion. It reaches the same final velocity in the same time as the second particle, where air resistance was not present.
(d)
Sketch the motion of this third particle on the graph in part (a).
A bird drops a spherical graphite rock of density 2230 kg m–3 and radius 3 cm vertically down a water well. After it hits the water surface, it rapidly reaches a terminal speed as it falls through the well.
(b)
Calculate the magnitude of the fluid resistance from the water on the rock whilst it travels at terminal speed.
The bird drops the rock 14 m above the water’s surface. is the time when the rock hits the water surface and is when the rock is at rest at the bottom of the well, which is 70 m deep.
One of the balls is now dropped from the same height again from rest. After 2 seconds, it enters a cylinder of oil where it then no longer accelerates.
(c)
Sketch on the displacement–time graph the motion of this ball.
A different ball, that is identical in every way but is much heavier than the first two is now dropped from a certain height. Again, after 2 seconds, it enters a cylinder of oil where it then no longer accelerates.
(d)
Compare and contrast how the displacement–time graph from part (c) would change for this heavier ball. Assume that air resistance is negligible.
and 
change with time t just before the ball hits the ground. 
