Ch 8: Fluids and Elasticity of Solids

Question 1

Tension is also known as ________ forces.
Compression is also known as _______ forces.
Shearing is also known as _______ forces.

Answer 1

stretching
squeezing
bending

p. 241

Question 2

What is the definition of/ equation for stress?

Answer 2

The magnitude of the force divided by the area over which it acts.

stress = force/ area

p. 242

Question 3

The formula for stress has area in the equation, but keep in mind that if you are given radius or diameter, realize that stress is inversely proportional to the ______ of the cross-sectional radius or diameter.

Answer 3

square

p. 242

Question 4

What is the formula for tensile or compressive strain?

Answer 4

change in length / original length

• ΔL / L₀ *
  p. 242

Question 5

What is the formula for shear strain?

Answer 5

distance of shear / original length

X / L₀

Question 6

What helpful, yet imprecise mnemonic can you use to distinguish between stress and strain?

Answer 6

Stress is pressure. Strain is change.

p. 242

Question 7

The fact that steel has a shear modulus less than half of its Young’s modulus indicates….

Answer 7

….that it’s easier to bend steel than it is to stretch or compress it.

p. 243

Question 8

For tensile or compressive stress the constant of proportionality is called…

Answer 8

…Young’s modulus.

p. 242

Question 9

For a shear stress, the constant of proportionality is called…

Answer 9

…the shear modulus.

p. 243

Question 10

Bone is more resistant to _______ than to _______.

Answer 10

tension

compression

p. 243

Question 11

State Hooke’s Law.

Answer 11

stress = modulus x strain

OR

F/A = E (**ΔL/L₀)

OR

ΔL = FL₀/EA

(shear is essentially the same equation, except you would substitute the shear modulus)

p. 243