Question

John's car is stopped at a red light. When the light changes, the car accelerates to 45 miles per hour in 15 seconds. What is the approximate rate of change in the miles per hour that John's car accelerated? A) 3 miles per hour per second B) 12 miles per hour per second C) 15 miles per hour per second D) 30 miles per hour per second

Answer 1

Initial velocity of John's car (V1) = 0 miles per hour
Final velocity of John's car (V2) = 45 miles per hour
Time taken for acceleration = 45 seconds
Then
Acceleration = (V2 - V1)/Time taken
                     = (45 - 0)/15 miles per hour per second
                     = 45/15 miles per hour per second
                     = 3 miles per hour per second.
So the approximate rate of change in the miles per hour that John's car accelerated is 3 miles per hour per second. The correct option among all the options given in the question is option "A".

Answer 2

The answer is 3 miles per hour.

You add 15+15+15 and you get 45