Chapter 8: Physics of Matter

Define Stress

• cross sectional area per volume

• mass per unit volume

• extension per unit length

• force acting per unit cross sectional area

When an object is under stress,

• It deforms

• It undergoes strain

• It change its shape/size

• All of the answer

Stress is ...

• the process by which the shape of a rock changes because of stress

• the amount of force per square unit area on a given material

• stress that occurs when an object is stretched

• stress that occurs when an object is squeezed

Select all the correct units for stress.

• Pa

• Nm^-2

• Nm²

• No unit

What is the correct unit for strain?

• Pa

• Nm^-2

• No unit

• Nm²

If the material recovers the original dimensions, when an external load is removed, this deformation is known as ______ deformation

• plastic

• permanent

• elastic

• reversible

Which letter is pointing to the elastic limit?

• A

• B

• C

• D

Which section reversible ?

• A

• B

• C

• D

A ductile material ...

• breaks without deforming

• changes its shape and size before breaking

What is material B?

• Plastic

• Cast iron

• Glass

• Titanium