Topic 8: Physics of matters

What is the correct unit for strain?

• Pa

• Nm^-2

• No unit

• Nm²

The Young's Modulus is defined as...

• The gradient of a stress strain graph

• The energy required to stretch a material.

• Stress/Strain

• Force/Extension.

Hooke's law states that

• the extension is proportional to the load when the elastic limit is not exceeded

• the extension is inversely proportional to the load when the elastic limit is not exceeded

• the extension is independent of the load when the elastic limit is not exceeded

• load is dependent on extension

At ‘yield point’ of a copper wire

• the load hasn't exceeded the elastic limit yet; so, Hooke's law applies

• the load has already exceeded the elastic limit and the material has become plastic

• even the plastic stage has passed and the wire has snapped already

• Like Brass and Bronze, Copper has no yield point

Substances that elongate considerably and undergo plastic deformation before they break are known as

• brittle material

• ductile material

• stiff material

• plastic material

• X- Glass, Y- Copper, Z- Rubber

• X- Glass, Y- Rubber, Z- Copper

• X- Rubber, Y- Copper, Z- Glass

• X- Rubber, Y- Glass, Z- Copper

The unit of Young’s modulus of elasticity is:

• pascals

• metres

• dimension-less

• newtons

Which letter is pointing to the elastic limit?

• A

• B

• C

• D

Which letter is pointing to where the material will break?

• A

• B

• C

• D

The units for elastic potential energy are...

• Joules, J

• metres, m

• centimetres, cm

• kilograms, kg