Question

Example 3.4 A bail is thrown vertically
upwards with a velocity of 20 m st from
the top of a multistorey building. The
height of the point from where the ball is
thrown is 25.0 m from the ground. (a) How
high will the ball rise ? and (b) how long
will it be before the ball hits the ground?
Take g = 10 ms​

Answer 1

Explanation:

Time to reach maximum height can be obtained from v=u+at

0=20+(−10)t

t=2s

s=ut+0.5at2=20(2)+0.5(−10)(2)2=20m

Thus, total distance for maximum height is 45 m

s=ut+0.5at2

45=0+0.5(10)(t′)2

t′=3s

Total time= 3+2= 5s