Materials - Hooke's Law

Question 1

Hooke’s Law

what does Hooke’s law state

Answer 1

• Hooke’s Law states that the force is proportional to the extension.
• A spring or elastic object will apply an opposing force that is proportional to the extension or compression of the spring or elastic body.
• This fact is given by f = kx, where k is the spring constant and x is the extension of the spring

Question 2

Hooke’s Law with a spring

Answer 2

• When a spring is compressed or stretched there will always be a force that tries to return the spring to its unstretched length
• The magnitude of the force trying to achieve this result is always proportional to the extension of the spring, meaning that as the extension increases, so does the force acting against its extension.
• As the equation to determine the force causing the extension is F = kx, you would also need an equation to find the spring constant, k.
• k can be found by using the equation k = λ/l, where λ is the spring modulus and l is the natural length.

Question 3

Potential Energy of a Spring

Answer 3

• A force must be applied to compress or extend a spring. If one end of the spring is fixed, this force will act over a certain distance and will do work; this work increases the potential energy of the spring.
• To find work done, you would use the equation W = average force * distance.
• For a spring compressed or extended from its rest length, the force is proportional to the extension and so the average force is given by Favg = 1/2kx. The work done and therefore the potential energy can be given by W = U = 1/2 * k * x^2