Question

From the top of a bulding 40m tall, a boy projected a stone vertically upward with an initial velocity of 10m/s . After how long will it pass thorugh the point from where it was projected

Answer 1

We know
v= u+at
Putting the above during the time of ascent, we have,
V=0
U= 10m/s
a= -10
So t=1s
We also know that tome of acent = time of descent.
Therefore total time to reach =2s
* the thing to know that the height of tower is not required for this particular question.
Hope this helps!