Question

A person throws a stone upwards and it reaches maximum height after 20second. If the acceleration due to gravity is *-10m/s²* then find the initial velocity with which it is thrown upwards.​

Answer 1

Question

A person throws a stone upwards and it reaches maximum height after 20second. If the acceleration due to gravity is *-10m/s²* then find the initial velocity with which it is thrown upwards.

Given

Time(t) = 20s

g = -10 m/s s

initial velocity(u) = ?

We know that,

v = u - gt (for a body thrown vertically upwards)

At maximum height , velocity of body = 0

0 = u - 10(20)

- u = - 200

u = 200 m/s

Therefore, the velocity with which the stone is thrown up is 200 m/s

• You can also remember the following formulas for fast and easy calculation

1. $time \: \: of \: ascent \: = \frac{u}{g}$
2. $time \: of \: descent \: = \frac{u}{g} = \sqrt{ \frac{2h}{g} }$

Note :-

In the solution,

u = initial velocity

v = final velocity

t = time

g = acceleration due to gravity

h = maximum height