A ball is thrown vertically upwards with a velcotiy of `20 ms^(-1)` from the top of a multi-storey building. The height of the point fromwher the ball is thrown if 25m from the ground. (a) How high the ball will rise ? And (b) how long will it be before the ball hits the ground ? Take. `g=10 ms^(-2)`.

Explanation

Here u=+20`ms^(-1),g=-10ms^(-2)`
At the highest point v=0
Suppose the ball rises to the height h from the point
of projection
As `v^2-u^2=2gs`
`:." "0^2-20^2=2xx(-10)xxh`
or h=+20m