Question

A 150 N boy rides a 60 N bicycle a total of 200 m at a constant speed. The frictional force against the forward motion of the bicycle equals 35 N. How much work does the boy do? (Hint: Do sum of all forces first.)

Answer 1

W = 7000 J

Step-by-step explanation:

To solve this problem we use that the speed of the bicycle is constant, therefore its acceleration is zero

F -fr = 0

F = fr

where F is the force applied by the child

Work is defined by

W = F. x

W = F x cos θ

in this case the child's force is parallel to the movement, therefore the angle is zero and cos 0 = 1

let's calculate

W = 35 200

W = 7000 J