Question

A ball thrown vertically upwards return to its starting point in 4s. If g= 10 m/s^2 , find its initial speed. ​

Answer 1

EXPLANATION:-

Here V=0

U=?

a=-10m/s^-1

Therefore from this we can say it take 2 second to rise to maximum height and in next 2 second it falls from maximum height to the position where it is thrown(this is because time of accent = time of decent).

So using first equation of motion:-

v=u+at

0=u+(-10)(2)

0=u-20

u=20 m/s

So the initial velocity is 20 m/s

Answer 2

Answer:

20m/s^ if u need explaination see the above picture