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Q11 CQ

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Found in: Page 315

### College Physics (Urone)

Book edition 1st Edition
Author(s) Paul Peter Urone
Pages 1272 pages
ISBN 9781938168000

# Why are the forces exerted on the outside world by the limbs of our bodies usually much smaller than the forces exerted by muscles inside the body?

The limbs in the human body are the third-class lever.

See the step by step solution

## Step 1: Force

A force is an external factor that can change the rest or motion of a body. It has a size and a general direction.

## Step 2: Explanation

The mechanical advantage of a machine is,

$MA=\frac{{F}_{\circ }}{{F}_{i}}\phantom{\rule{0ex}{0ex}}=\frac{{l}_{i}}{{l}_{\circ }}$

For,${l}_{i}<{I}_{\circ }$, ${F}_{i}>{F}_{\circ }$.

The elbow serves as the fulcrum if a load is on the palm. The effort is applied by flexing the biceps. The force exerted by the muscles is the input force, and the force applied by the limbs on the outside world is the output force. As ,${l}_{i}<{I}_{\circ }$ the input force is always more significant than the output force. The human limbs are the third-class lever.