Vertical motion

velocity versus time for the plastic ball

The vertical velocity in metres per second versus the instant of time in seconds after launching (at t=0) the plastic ball with an initial upward speed of v0=20 m/s.

The expressions which relate the velocity as a function of time for the vertically moving solid metal ball close to the surface of earth do certainly NOT apply in this case.

Below we compare the two cases in one graph.

The vertical velocity in metres versus the instant of time in seconds after launching (at t=0) a solid metal ball and a plastic ball both with an initial upward speed of v0=20 m/s.