Question

A ball thrown vertically upwards from ground

Answer 1

parabolic motion

$\tt t_{max}=\dfrac{2u~sin~\alpha }{g}$

$\tt h_{max}=\dfrac{u^2sin^2\alpha }{2g}$

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

$\tt 4=\dfrac{2u}{10}\rightarrow u=20~m/s$

$\tt h_{max}=\dfrac{20^2}{2.10}=\boxed{\bold{20~m}}$