Question

A ball is thrown vertically upwards and rises to a height of 126.5 m. Calculate the
(i) velocity by which the ball was thrown upwards and
(ii) the time taken by the ball to reach the highest point.

Answer 1

Explanation:

( 1 ) V=0 as after reaching max. height the ball will stop , u = ? , h = 126.5 m

therefore , by third eqn. of motion ,

v^2 = u^.2 + 2gs

0 = u^2 + 2*10*126.5

hence , u = √2530

u = 50m/s (approx.)

(2 ) t = ? , u = 50 , g = 10m/s

by 2 eqn. of motion or 1 eqn. of motion

s = ut + 1/2 gt^2 (or ) v = u + at

t = 5 seconds...