Investigating Elasticity

Question 1

True or false? The work done to elastically stretch a spring is equal to the elastic potential energy stored in the spring.

Answer 1

True

The word ‘elastically’ is crucial here. If the spring isn’t elastically distorted, it won’t be true

Question 2

A linear force-extension graph means that force and extension are which of the following? A: not proportional B: directly proportional C: inversely proportional

Answer 2

B

A linear force-extension graph will be a straight line through the origin

Question 3

A spring has a spring constant of 50N/m. Calculate the energy stored in the elastic potential energy store of the spring after it has been elastically distorted to an extension of 10cm. Use the following formula:

energy transferred in stretching = 1/2 x spring constant x (extension)^2

Answer 3

ANSWER: 0.25J
METHOD:10cm = 0.1m, so the energy transferred in stretching the spring is 1/2 x 50 x 0.01^2 = 25 x 0.01 = 0.25J

Because the spring was elastically distorted the energy stored in the elastic potential energy store of the spring is also 0.25J