Question

A crowbar of length 120 cm has its fulcrum situated at a distance of 20 cm from the load. Calculate the effort arm and the mechanical advantage of the crowbar.

• A. Effort arm = 20 cm, Mechanical advantage = 1
• B. Effort arm = 20 cm, Mechanical advantage = 1.6
• C. Effort arm = 30 cm, Mechanical advantage = 1
• D. Effort arm = 100 cm, Mechanical advantage = 5

Answer 1

Answer: (D)

Effort arm = 100 cm, Mechanical advantage = 5

The crowbar is a class I lever as the fulcrum is situated in between the load and effort.

Here, load arm = 20 cm

Effort arm = 120 - 20 = 100 cm

So, $MA=\frac{Effortarm}{Loadarm}=\frac{100}{20}=5$