Question

with what velocity should a body be thrown vertically upwards so that it reaches a height of 25m ? For how long will it be in the air?

Answer 1

use newton's formula here: v²=u²+2as

v=final velocity=0m/s

u=initial velocity=to be determined

a=acceleration= -10m/s²(since it is against gravity)

s=displacement=25m

∴u=√500=22.4m/s

Answer 2

v^2=u^2+2as

0=u^2+2*-10*25

u=22.13m/s

time=25/22.13

       =1.12sec