# Question #75e5d

##### 1 Answer

The answer is **d)** *7 seconds*.

#### Explanation:

Because the ball was launched at a *vertical component* and *horizontal component*.

Since you have no information about the distance from the tower the ball travelled in its flight, you're going to have to turn to the *vertical component* of its trajectory.

So, **vertically**, the ball starts at a height of **70 m**. This means that, when it reaches *ground level*, the total *vertical displacement* will be equal to **-70 m**.

Think of its like this - when it hits the ground, the ball is 70 meters *lower* than its starting position.

This means that you can write

Plug in your values into the above equation to get (use

Solving this quadratic equation will get you

Therefore, the ball reaches the ground in