Question

novak dgokovix can hit a serve close to 200km per hour (55.5 meters per second). find out how much time in seconds does it take the ball to reach the opponent who is 78ft away

Answer 1

First, convert 78ft into meters.

Recall that 1 meter = 3.28 ft

Convert and we get

`\begin{gathered} 78\text{ ft}\cdot\frac{1\text{ m}}{3.28\text{ ft}} \\ =78\cancel{\text{ ft}}\cdot\frac{1\text{ m}}{3.28\cancel{\text{ ft}}} \\ =\frac{78\text{ m}}{3.28} \\ =23.78\text{ m} \end{gathered}`

Next, divide 23.78 m, to the speed novak dgokovix can serve

`\begin{gathered} 23.78\text{ m}/55.5\text{ m/s} \\ =23.78\text{ m}\cdot\frac{1\text{ s}}{55.5\text{ m}} \\ =23.78\cancel{\text{ m}}\cdot\frac{1\text{ s}}{55.5\cancel{\text{ m}}} \\ =\frac{23.78\text{ s}}{55.5} \\ =0.4284684\text{ s} \end{gathered}`

Rounding to two decimal places, it will take 0.43 seconds for the ball to reach the opponent.