Chapter 10, Problem 25SGR

To determine

The velocity of the car in miles per hour.

Answer to Problem 25SGR

  $24\text{mph}$

Explanation of Solution

Given information:

  $\text{Distance}=100\text{feet}$

  $\text{Time}=2.8\text{seconds}$

Calculation:

In order to find the velocity of the car in miles per hour, first putting the value of distance, that is 100 feet and the value of time, that is 2.8 seconds after that convert the unit ft/sec to miles per hour, first convert ft/sec to ft/min by using 1 min is equal to 60 seconds, then convert feet/min to feet/hr by using 1 hour is equal to 60 min and then convert feet per hour to miles per hour by using 1 mile is equal to 5280 feet to simplify further as shown below:

  $\begin{array}{l}\text{velocity}=\frac{\text{distance}}{\text{time}}\\ v=\frac{100\text{ft}}{2.8\sec }=35.714\frac{\text{ft}}{\sec }\\ 35.714\frac{\text{ft}}{\sec }\times \frac{60\sec }{1\min }=2142.857\frac{\text{ft}}{\min }\\ 2142.857\frac{\text{ft}}{\min }\times \frac{60\min }{\text{1hr}}=128571.42\frac{\text{ft}}{\text{hr}}\\ 128571.42\frac{\text{ft}}{\text{hr}}\times \frac{1\text{mile}}{5280\text{ft}}=24.35\frac{\text{miles}}{\text{hr}}\\ v\approx 2\text{mph}\end{array}$

Thus, the velocity of the car is approximately $24\text{mph}$ .