CHAPTER 7. MECHANICAL PROPERTIES OF MATTER 7.2
DEFINITION: Hooke’s Law
In an elastic spring, the extension varies linearly with the force applied.
F =−kx
where F is the restoring force innewtons (N), k is the spring constant
in N·m−^1 and x is the displacement of the spring from its equilibrium
length in metres (m).0
1
2
3
4
0 0 .1 0.2 0.3 0. 4
����Force (N)Extension (m)Figure 7.1: Hooke’s Law- the relationship between a spring’s restoring force and its
displacement from equilibrium length.
Activity: Hooke’s Law
Aim:
Verify Hooke’s Law.
Apparatus:- weights
- spring
- ruler
Method:
- Set up a spring vertically in such a way that you are able to hang weights
from it. - Measure the equilibrium length, x 0 , of the spring (i.e. thelength of the
spring when nothing is attached to it). - Measure the extension of the spring for a range of different weights. Note:
the extension is the difference between the spring’s equilibrium length
and the new length when a weight is attached toit, x− x 0. - Draw a table of force(weight) in newtons andcorresponding extension.
- Draw a graph of force versus extension for your experiment.