Question

A crowbar is used to pull a nail. The length of the effort arm of the crowbar is 28 cm and the resistance arm is 4.2 cm. What force in N is required to pull a nail if the friction force holding the nail in place is 120 N?

Answer 1

18N

Step-by-step explanation:

Mechanical Advantage of crowbar (lever), MA = Length of effort arm / Length of resistance arm

Therefore, MA = 28 cm / 4.2 cm = 6.667

Force required to pull the nail, F = Friction force / MA

ie, F = 120 N / 6.667 = 18 N