- #1

- 1,833

- 180

## Homework Statement

A three-legged stool has one leg of aluminium (E = 7 x 10

^{10}Pa), one copper (E = 11 x 10

^{10}Pa) and one of steel (E = 20 x 10

^{10}) Pa. The legs have the same dimensions. If the load on the stool is at the exact center,

a. Which leg is under the greatest stress? Explain why

b. Which leg experience the greatest strain? Explain why

## Homework Equations

stress = force / area

strain = extension / original length

young modulus = stress /strain

force = (E.A.extension) / original length

## The Attempt at a Solution

a. All the legs have same dimensions means that the area are the same, so the stress is directly proportional to the force. Assuming they all have the same extension, then the force is directly proportional to young modulus. So the steel is under the greatest stress

b. Because all the legs have same extension and original length, the strain experienced is the same for all

Am I correct? I am really not sure, especially about the assumption that the extension is the same for all.

Thanks