Elasticity

Question 1

Elastic deformation

Answer 1

When an object is deformed elastically, it will return to its original shape if the forces acting on it are removed

The amount of work done on the object will be equal to the amount of elastic potential energy which has been stored in it as a result of its change in shape

Question 2

Inelastic deformation

Answer 2

When an object is deformed inelastically, it will NOT return to its original shape if the forces acting on it are removed

Some of the energy put into changing the shape of the object will be used in reorganising the particles inside it so that it won’t return to its original shape

Question 3

Hooke’s law

Answer 3

The extension of a spring is directly proportional to the force applied to it (so long as the limit of proportionality has not been exceeded)

Question 4

Spring constant equations

Answer 4

Force (N) = spring constant (N/m) x extension (m)
Elastic potential energy (J) = 0.5 x spring constant (N/m) x extension (m^2)

Question 5

Limit of proportionality

Answer 5

The point beyond which the force applied to an object is no longer directly proportional to the extension

Question 6

Elastic limit

Answer 6

The point at which the object has been plastically deformed/ broken

Question 7

Core practical - investigate the extension when applying forces to a spring

Answer 7

1) wear safety glasses to protect the eyes and make sure the clamp is secure
2) measure the position of the bottom of the spring against the metre rule
3) attach a 100g mass to the spring and measure the new position of the bottom of the spring against the metre rule
4) calculate the extension by doing current position - original position
5) repeat with additional masses
6) plot a extension-force (force (N) = mass (kg) x 10) graph and they should be directly proportional