Question

A block and tackle is used to lift an automobile engine that weighs 1800 N. The person exerts a force of 300 N to lift the engine. How many ropes are supporting the engine? (Remember that AMA = force output/force input.)

Answer 1

Answer:

6

Explanation:

The mechanical advantage of a machine is defined as the ratio between the output force and the input force:

$MA=\frac{F_o}{F_i}$

In this problem, we have

$F_o = 1800 N$ is the output force

$F_i=300 N$ is the input force

So, the mechanical advantage is

$MA=\frac{1800 N}{300 N}=6$

Moreover, the mechanical advantage of a pulley system is also equal to the number of ropes supporting the load. In this case, the mechanical advantage is 6, therefore the pulley system must have 6 ropes.