Question

From the top of the building 40m tall a boy projected a stone vertically upwards with an initial velocity of 10m/s such that it eventually fall on the ground. at what ime stone reach the groung . g=10m/s2

Answer 1

Answer:

s=−40m,u=+10m/s,a=−10m/s

2

Now s=ut+(1/2)at

2

=> −40=10t+1/2×(−10)t

2

=> t

2

−2t−8=0

=> (t+2)(t−4)=0

=> t=−2,4s

The negative value of t is not possible

Hence the ball will hit the ground after 4s