Question

Questions a) A stone is thrown vertically upwards It goes to a height of 20 m and then comes back to the ground Find
the initial velocity of projection
) the total time of journey iii )the velocity at which the stone strikes the ground.
(Take g =10 m/s^2)​

Answer 1

Explanation:

here S=20m,a=10m/s²,v=0

v²-u²=2as

-u²=2×10×20

-u²=400

u=20

1) initial velocity of projection=20

next u=20,v=0,a=10m/s²

v=u+at

0=20+10t

10t=-20

t=-2s

2)total time of journey =-2s

S=(v+u)/2×t

S=(v+20)/2×-2

20=(v+20)×-1

-20=v+20

v=40m/s

3) velocity at which it strikes the ground is 40m/s