Elasticity

Question 1

What are the three forces which can cause a stress on an object?

Answer 1

Tension, Compression and Shear

Question 2

What is elasticity and gives examples of objects which are elastic?

Answer 2

The property of an object to return to its original dimensions after distorting forces are removed.
-rubber, springs

Question 3

What will occur if f the distorting force exceeds the objects elasticity limit?

Answer 3

Then a permanent distortion will occur.

Question 4

One object is said to be more elastic…

Answer 4

if it returns to it’s original shape with greater precision

Question 5

How is something more elastic?

Answer 5

Steel is more elastic than rubber because steel comes back to its original shape faster than rubber when the deforming forces are removed

Question 6

What is periodic motion?

Answer 6

Motion that repeats itself at regular intervals.

Question 7

What is period?

Answer 7

The time required to complete one full cycle, abbreviated “T”
-Unit of time (seconds)

Question 8

What is frequency?

Answer 8

Number of cycles completed in one second, abbreviated “F.”
Frequency is measured in Hertz (Hz).
-F = Hz

Hooke’s Law
•Within its limit the deformation of an elastic solid is proportional to the deforming force.

•If you double the deforming force you will double the deformation

Question 9

What is amplitude?

Answer 9

• Maximum distance moved from the equilibrium point

- Measured as distance

Question 10

How is Hooke’s law written?

Answer 10

F = -kx
Where: F = deforming force
-k = proportionality constant
x = amount of stretch

Question 11

What is young’s modulus?

Answer 11

Young’s Modulus (E) or the modulus of elasticity is a measure of a materials stiffness. The higher the Young’s modulus value the stiffer the material.

Question 12

How can young’s modulus be calculated?

Answer 12

Young’s modulus can be calculated from tensile test stress/strain graphs–derived from load/extension graphs. The slope of the graph is used to calculate E when the material is obeying Hooke’s law.

Question 13

What is tensile and compressive stress?

Answer 13

Tensile means there is an increase in length of the object, and compressive is a decrease in length.

Question 14

What is stress and strain?

Answer 14

Stress is an internal force per unit area, and the deformation the object undergoes due to the stress is the strain