Question

An object thrown vertically upwards reaches a height of 500m. What was its initial velocity? Haw long will the object take to come back to the earth? Assume g=10m/s²

Answer 1

Let the initial velocity =u
final velocity = v

v= 0 m/s
s = 500 m 

2gs = v square - u square

2 (-10) 500 = u square
u= 100 m/s


v= u +at
0=100 - 10 t
t = 10 s

total time taken = 20 sec.

Answer 2

H=u*u/2*g
500=u*u/2*10
u*u=10000
u=10m/s