# A ball is thrown vertically upwards from a window that is 3.6m above the ground.The ball's initial speed is 2.8m/s and the acceleration due to gravity is 9.8m/#s^2#. What is the ball's speed when it hits the ground?

##### 1 Answer

Speed upon impact: **8.9 m/s**

#### Explanation:

You know that your ball is being thrown from a height of **3.6 m** with an initial velocity of **2.8 m/s**.

At the top of its motion, i.e. at *maximum height*, the velocity of the ball will be **zero**. This means that you can determine the height it travels *before* starting its decent by using the initial velocity

This is equivalent to

The ball will be at a total height of

Now use the same equation again, only this time take into account the fact that the *initial* velocity, i.e. the velocity at maximum height, is zero.