Hooke's law

Question 1

What is Hooke’s Law?

Answer 1

Force is DIRECTLY PROPORTIONAL to extension (up to the elastic limit)

Question 2

What does a material that obeys Hooke’s Law look like on a force-extension graph?

Answer 2

Straight line (through the origin)

Question 3

What is an elastic material?

Answer 3

A material that goes back to its original shape after the deforming force has been removed

Question 4

Where does the material stop becoming an elastic material?

Answer 4

Elastic limit- Where it stops being elastic anymore

Question 5

What does Hooke’s Law state?

Answer 5

Hooke’s Law state that for a spring, F=kx where F is the force applied to the spring, k is the spring constant, and x is the extension

Question 6

What does a linear force-extension graph show?

Answer 6

Straight line

Question 7

What is the point when it stops being linear called?

Answer 7

The limit of proportionality, from then on it does not obey Hooke’s Law

Question 8

Outline the basic steps of the practical

Answer 8

Equipments required:

Masses
Spring
Clamp stand
Ruler
Goggles

Method

1. Hook spring onto clamp stand and measure original length.
2. Hook 1 mass onto the spring and measure new length and calculate the extension
3. Repeat this step until elastic limit is reached
4. Record results in table and draw force Vs Extension graph

Conclusion

Force and extension are directly proportional until the elastic limit is reached

Question 9

What piece of apparatus is used to secure the clamp stand to the desk and why?

Answer 9

A G-Clamp, so that the clamp doe not tip over whilst adding masses

Question 10

How do you calculate the extension of the spring when you add masses?

Answer 10

Subtract the extended length of the spring from the original unstretched length

Question 11

What can you add to the spring to ensure that the extension measurements are accurate?

Answer 11

A pointer attached horizontally to the base of the spring and extending across the metre rule. This will make reading the length easier.

Question 12

What piece of safety equipment should be used throughout this experiment and why?

Answer 12

Safety glasses should be worn in case the spring breaks or becomes unattached and damages your eyes

Question 13

What other safety precautions should be taken?

Answer 13

You should avoid standing with your feet underneath where the weights are hanging in case they fall

Question 14

What graph should you plot with your results? What would you expect it to look like?

Answer 14

1. Extension against force
2. You would expect it to be a straight line passing through the origin. The variables should be directly proportional

Question 15

What is the name of the relationship between extension and force? State the relevant equation

Answer 15

Hooke’s Law

Force= Spring constant x Extension (F=KE)

Question 16

What type of energy is stored in the spring as it is stretched

Answer 16

Elastic potential energy

Question 17

What equation can be used to calculate the elastic potential stored in the spring?

Answer 17

Elastic Potential energy = 1/2 x Spring constant x Extension

E= 1/2 kx

Question 18

How can you use your apparatus and graph to work out the weight of an unknown object?

Answer 18

1. Hang the object on the spring and record the extension it produces
2. Draw a line from that extension on your graph until it meets your plotted line and then read off the corresponding weight.