# A stone is thrown vertically upwards and it reaches a maximum height of 30m. What was its initial velocity?

##### 1 Answer

#### Explanation:

A stone is thrown vertically upwards. So that the only force acting on the stone is the Gravitational force . we consider the the upward directions as positive y-axis . Then there is no motion is along x-axis. And the acceleration of the stone is -g

```
where
g is acceleration due to gravity
```

the negative indicates that the acceleration is along negative y-axis (towards downward direction).

The equation of motion connecting the velocities and the displacement of the particle is given by

Here

v is the final velocity,

u is the initial velocity( velocity with which the stone is thrown)

a is the acceleration . here (-g, acceleration due to gravity),

S is the displacement . here(Maximum Height reached by the stone)

```
At the maximum height velocity becomes zero ( v=0)
```

SUBSTITUTE VALUES IN THE EQUATION

Therefore the velocity with which the stone thrown is