Forces and Elastic

More than one force must be applied

Stretching - forces in opposite directions away from the object
Bending - forces that distort the object
Compressing - forces in opposite directions towards the object

Elastic or inelastic

Obiects return to their original shape when the stretching force is removed

Rubber band
Fabric
Steel spring

When objects remain stretched and do not return completely to their original shape even when the stretching force is removed

Plastic
Clay
Glass

The extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality

If more force is added, the object may extend but will not return to its original shape when the force is removed

F = kx
Force = spring constant(N/m) * extension (m)

There is a non linear relationship between force and extension

The graph is straight but does not necessarily pass through the origin

Work is done by the spring( ie energy is transferred to the EPE store of the spring)

Are equal

E = 1/2 * k * x^2

Independant - force
Dependant - extension
Control - spring constant k

Clamp and stand (hold spring and masses)
Ruler (measure extension)
Spring (measure extension of this)
5 * 100g masses ( to apply a force to the spring)
100g mass hanger ( to hold additional masses)
Fiducial marker - to accurately read extension from ruler

1. Set up apparatus (view diagram in notes)
2. Align marker to a value on the ruler, recording this initial spring length
3. Add the 100g mass hanger onto the spring and record the position now that the spring has extended
4. Add another. 100g and record the new mass and position
5. Repeat until all masses are added
6. Remove masses and repeat three times to calculate an average length

W = mg