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)

0.0000.2000.4000.6000.8001.000

0 N 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