Question

A soap box derby is a contest in which the cars competing rely only on gravity to move. There is nothing motorized in the car. These gravity racers are typically either pushed by others at the start of a race or the race is downhill.

DeMarius is constructing a car to enter into a soap box derby. The side panel of the car is shown.

1. The rear wheels of DeMarius’ car complete 4/5 of a rotation for every full rotation of a front wheel. What is the radius, in feet, of a rear wheel on the car? Write your answer as a simplified fraction.

Answer 1

Let Radius of Front wheel = r

Let the radius of rear wheel = R

We know, one full rotation for a wheel will be equal to its circumference/parameter.

As per informaion given in quesion

Full rotation of front wheel = 4/5 rotation of rear wheel

2r = (4/5)2R

Dividing by 2 on both sides

We get R=(5/4)r

r either can be given or can be found from side panel of car which is not provided in question.