Question

While standing on the roof of a building, a child tosses a tennis ball with an initial speed of 16 m/s at an angle of 20° below the horizontal. The ball lands on the ground 3.5 s later. How tall, in meters, is the building?m

Answer 1

75 m

Explanation

Step 1

let

$\begin{gathered} \text{angle to the horizontal=20\degree} \\ v_0=16\text{ m/s} \\ t=3.5\text{ s} \end{gathered}$

to solve this , we need use the formula:

$y=(v_0\sin \theta)+\frac{1}{2}gt^2$

replace to solve

$\begin{gathered} y=(v_0\sin \theta)t+\frac{1}{2}gt^2 \\ y=((16\sin 20)\cdot3.5)+\frac{1}{2}(9.81)(3.5)^2 \\ y=15.03+60.08 \\ y=75.055 \\ \text{rounded} \\ y=75\text{ m} \end{gathered}$

hence, the answer is 75 meters