Physics 3.4

Question 1

What is elastic and plastic deformation?

Answer 1

-Elastic: when the object returns to its original shape once the forces are removed e.g a cushion
-Plastic: The material has exceeded its elastic limit(the force which the atoms can’t return to their original shape) and the object will remain permanently deformed

Question 2

What will compressive and tensile forces cause a wire to do?

Answer 2

-Two equal and opposite tensile forces will cause a wire to extend
-Two equal and opposite compressive forces will causes the wire to decrease in length

Question 3

What is the gradient of a force extension graph?

Answer 3

The force constant

Question 4

Define stress and strain?

Answer 4

-Stress is the force per unit cross sectional area, it has the units n/m^2 or Pa
-Strain is the extension per unit length, It therefore doesn’t have a unit

Question 5

Do objects which are stiff have a large or small Youngs modulus?

Answer 5

-Stiff objects will have a large young modulus as a lot of stress(force per unit area) will cause less strain(extension)

Question 6

Define ductile, malleable, brittle, hard, stiffness?

Answer 6

-Ductile material can be drawn into wires and will show plasctic deformation under stress before breaking
-Malleable materials can be hammered into shape and will show lots of plastic deformation under stress before breaking
-Brittle material will break with little or no plastic deformation
-A hard material will resist plastic deformation by surface indentation
-Stiffness is the ability to resit a tensile force