Chapter 6.1, Problem 69CCR

To determine

Find the speed of the car in miles per hour. Also round off to the nearest tenth.

Answer to Problem 69CCR

The speed of the car is $62.0miles/hour$ .

Explanation of Solution

Given:

It is given in the question that a police officer notes that a car travelled $200$ feet in $2.2$ seconds.

Concept Used:

In this, use the formula of speed = Distance / time and also know to change the units.

Calculation:

Here, change the feet per second into miles per hour.

  $\frac{200feet}{2.2\sec }$

Multiply that by the number of seconds in an hour:

  $\frac{200feet}{2.2\sec }\cdot \frac{3600\sec }{1hour}$

And divide it by the number of feet per mile.

  $\frac{200feet}{2.2\sec }\cdot \frac{3600\sec }{1hour}\cdot \frac{1mile}{5280feet}$

The result will be:

  $\begin{array}{l}\frac{200\times 3600\times 1}{2.2\times 1\times 5280}miles/hour\\ =\frac{720000}{11616}\\ \approx 62.0miles/hour\end{array}$

Conclusion:

The speed is $62.0miles/hour$ .