Young's Modulus + Deformation

Plastic Deformation is when a material...

• becomes temporarily deformed

• loses elastic potential energy

• becomes permanently deformed

• gains kinetic energy

When an elastic band is stretched and contracted it forms a graph like this.

What does the area between the two lines (region X) represent?

• The work done needed to stretch the rubber band

• The heat energy produced in the rubber band

• The energy used to contract the rubber band

• The spring constant of the rubber band

A material is stretched and contracted by adding then removing a mass load from it. The graph is shown on the left.

What 2 things does this graph tell us about the material?

• The material does not obey Hooke's Law

• The material experiences plastic deformation when a load is applied

• The material experiences elastic deformation when a load is applied

• The material does obey Hooke's Law

Elastic Deformation is when a material...

• becomes temporarily deformed

• loses elastic potential energy

• becomes permanently deformed

• gains kinetic energy

During plastic deformation energy is not conserved, which is why we see a permanent extension in the material.

Which answer provides the best explanation for this?

• The energy is 'lost' because the material temporarily changes state to a liquid then back again

• The energy is 'lost' as heat to the surroundings

• The energy 'lost' is being used to vibrate the atoms in their positions

• The energy 'lost' is being used to reposition the atoms

The equation for stress is...

The gradient of the linear portion of a stress-strain graph is...

• The spring constant of the material

• The force per unit area

• The elastic strain energy per unit volume

• The Young's Modulus

The equation for strain is...

Which equations best describe Young's Modulus?

Which point on the graph best describes the yield point of this material?

• A

• B

• D

• E