Stretching and Compressing

Question 1

How many forces are required to compress, bend

or stretch an object?

Answer 1

More than one; it takes multiple forces (in

different directions) to deform an object

Question 2

Explain the relationship between the force applied

and the extension of an elastic object

Answer 2

The extension is directly proportional to
the force applied, provided that the limit
of proportionality is not exceeded

Question 3

What is meant by an inelastic (plastic) deformation?

Answer 3

● A deformation which results in the
object being permanently changed
● The object doesn’t return to its original
shape when the force is removed

Question 4

State the equation relating force, spring constant and

extension. Give appropriate units.

Answer 4

Force = Spring Constant x Extension

Force (N), Spring Constant (N/m)
Extension (m)

Question 5

What type of energy is stored in a spring when it is

stretched?

Answer 5

Elastic potential energy

Question 6

What can extension be replaced with in the equation

for spring force?

Answer 6

Compression

Question 7

Differentiate between elastic and inelastic

distortion

Answer 7

An elastic distortion is a temporary change. The
object reverts to its original shape once the forces
are removed. An inelastic distortion leads to a
permanent change in shape. It is irreversible.

Question 8

How can you calculate the work done/stored in

stretching a spring?

Answer 8

Energy (J) = ½ x Spring constant (N/m) x Extension² (m²)

E = ½kx

Question 9

When is there a linear relationship between force and

extension?

Answer 9

When an object is deforming elastically;
when it has not yet reached the limit of
proportionality.

Question 10

When is there a nonlinear relationship between force

and extension?

Answer 10

When the limit of proportionality has
been exceeded, and the object is
undergoing plastic deformation.