The average speed of the model car is found by dividing the total distance traveled by the car by the total time the car traveled. In the first t seconds after the car starts,the time changes from 0 to t seconds. So the total distance the car traveled is the distance it traveled at t seconds minus the distance it traveled at 0 seconds. At 0 seconds, the car has traveled
16(0)√0 inches, which is equal to 0 inches. According to the equation given, after
tseconds, the car has traveled
16t√t inches. In other words, after the car starts, it travels a total of
16t√t inches in t seconds. Dividing this total distance traveled by the total time shows the car’s average speed:
=16√t inches per second.
Choices A, C, and D are incorrect and may result from misconceptions about how average speed is calculated.