Question

A ball thrown vertically upwards with a speed of 20 ms^-1 from the top of a tower returns to the earth in 8 s. Find the height of the tower. Take g — 10 ms^-2

Answer 1

Answer: 160m

Explanation:

The time taken for ball to return to Earth = 8 sec

The maximum height achieved at time = Total time taken /2

                                                                 =8/2  = 4sec

u=20m/s

t=4sec

a=10m/sec^2

s=?

s = ut + 1/2 a t^2

   =20 * 4 + 1/2 * 10 * 4^2

   = 80 + 80

   = 160m

Hope this helps