HOOKE’S LAW
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
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
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
0N
0m = equilibrium
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
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:
1) Describe the shape of the graph. What is the
relationship between the extension and the
applied force?
2) Determine the equation of the graph. What
does the slope represent?
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
EP = ½ kx2