Question

A ball thrown vertically upwards from ground

level hits the ground after 4 s. Calculate the
maximum height it reached during its journey.
(SC/GCE)

Answer 1

parabolic motion

`\tt t_(max)=(2u~sin~\alpha )/(g)`

`\tt h_(max)=(u^2sin^2\alpha )/(2g)`

vertically upwards ⇒ α = 90°⇒sin 90° = 1

`\tt 4=(2u)/(10)\rightarrow u=20~m/s`

`\tt h_(max)=(20^2)/(2.10)=\boxed{\bold{20~m}}`