Question

Jeff is a landscaping contractor and lifts a rock weighing 600 pounds by wedging a board under the rock. Jeff weighs 150 pounds and puts all of his weight on the lever. How much mechanical advantage did the lever provide to Jeff in lifting the rock? A) 0 B) 2 C) 4 D) 8

Answer 1

Answer: 4

The mechanical advantage is the ratio of the force exerted  by the object to the force applied to do work on it.

Here, Jeff tried to lift a rock weighing 600 pounds by wedging board under the rock. Jeff who weighs 150 pounds uses all his weight to exert force on lever and lift rock.

Mechanical advantage, $M.A.=\frac{weight\hspace{1mm}of\hspace{1 mm}rock}{weight\hspace{1mm}of\hspace{1 mm}Jeff}=\frac{600 pounds}{150 pounds}=4.$

Therefore, the mechanical advantage that lever provided to Jeff in lifting rock is 4.

Answer 2

Answer: 4

The lever enabled Jeff to lift 600 pounds with merely 150 pounds.
By definition, the mechanical advantage is 600/150 = 4.