Question

A joker throws four balls in air at regular interval of time such that maximum height of each ball is 5 m. When the first ball leaves his hand, the positions of other three balls are –

• A. 15 m, 20 m, 15 m
• B. 3.75 m, 5 m, 3.75 m
• C. 1.25 m, 5 m, 1.25 m
• D. 2.5 m, 5 m, 2.5 m\

Answer 1

Answer: (B)

3.75 m, 5 m, 3.75 m

Answer 2

Initial velocity of each ball, u = $\sqrt{2gH}$ = 10 m/s

Time of flight of each ball, T = $\frac{2u}{g}$ = 2s

Time interval between successive ball,

t = $\frac{2}{4}$ = 0.5 s

 h = ut –$\frac{1}{2}$ gt²

= 10 t – 5t²

 t = 0.5s, 1s, 1.5 s

h = 3.75 m, 5m, 3.75m