1. HOOKE’S LAW

2. SIR ROBERT HOOKE (1635-1703) English Biology: “cell”, evolution
Chemistry: vacuum, Boyle’s law
Physics: Refraction and wave theory of light, gravity, law of elasticity

3. Law of Elasticity: “Hooke’s Law”
F= -kx
F = restoring force of spring
x = the distance that the spring has been stretch or compressed from equilibrium
k = the spring constant
(-) = force acts in opposite direction of the displacement

4. Extension of Spring (m)
Lab Activity p 255
Prepare a data table:
Mass (kg)
Applied Force (N) =Fg
Extension of Spring (m)
0.000
0.200
0.400
0.600
0.800
1.000
0 N
0m = equilibrium

5. Lab Activity p 255
Gather: a ring stand, meter stick, spring, tape, set of masses (100g, 2 x 200g, 500g, 1kg)
Attach the meter stick to a desk or lab bench
Hang the spring on the ring stand and position it such that the end of the spring with no mass attached is lined up with the ZERO
Hang masses and record the extension

6. Lab Activity p255
Create a graph of the applied force vs the extension.
NOTE: put the extension on the x-axis and the force on the y-axis
QUESTIONS:
Describe the shape of the graph. What is the relationship between the extension and the applied force?
Determine the equation of the graph. What does the slope represent?

7. ELASTIC POTENTIAL ENERGY
You can use the graph of Hooke’s Law to determine the quantity of potential energy stored in the spring.
Calculate the area under the force vs position graph
Ee = ½ kx2