6. Materials

Question 1

What are tensile forces?

Answer 1

Forces that produce extension

Question 2

What are compressive forces?

Answer 2

Forces that shorten an object

Question 3

What is Hooke’s law?

Answer 3

The extension of the spring is directly proportional to the force applied.
This is true as long as the elastic limit of the spring is not exceeded

Question 4

Describe the characteristics of a force-extension graph for a spring

Answer 4

A straight line from the origin up to the elastic limit of the spring.
(the spring undergoes elastic deformation)
Beyond the elastic limit, the spring undergoes plastic deformation.
(and the spring will not return to its original shape when the force is removed)

Question 5

What is the force constant?

Answer 5

A measure of the stiffness of a spring
(the larger the force constant, the stiffer the spring)

Question 6

What are the steps to investigation Hooke’s law?

Answer 6

1. Attach the spring at one end using a clamp, boss, and clamp stand secured to the bench using a G-clamp or a large mass
2. Set up a metre rule with a resolution of 1mm close to the spring
3. Suspend slotted masses from the spring and, as you add each one, record the total mass added and the new length of the spring

Question 7

How can you improve the accuracy when investigation Hooke’s law?

Answer 7

• Take readings at eye level
• Set square for length measurements
• Measure masses using a digital balance

Question 8

How can you ensure reliable results when investigating Hooke’s law?

Answer 8

Take at least 6 different readings and repeat each one atleast once

Question 9

What is the equation for elastic potential energy?

Answer 9

E = 1/2 Fx^2

Question 10

What cannot be fully recovered if a material has been extended or compressed beyond its elastic limit?

Answer 10

Work done