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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

PLEASE REQUEST DEMOS WELL IN ADVANCE

Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Measurement
 Motion In One Dimension
 Motion In Two Dimensions
 Newton's First Law
 Newton's Second Law
 Newton's Third Law
 Statics Of Rigid Bodies
 Applications Of Newton's Laws
 Gravity
 Work and Energy
 Momentum
 Rotational Motion
 Properties of Matter
 Hooke's Law
 Force Constant of a Spring
 Spring Scale Collection
 Strings and Springs
 Breaking Wire (Plasticity)
 Bending Beams
 Prince Rupert's Drops
 Shear Block
 Happy and unhappy balls
  video  - Coefficient of Restitution
 Crystal Models

Force Constant of a Spring

Purpose:

To show the relationship of the force constant, k, of a spring to an applied force and to its potential energy.

Procedure:

  • Method 1:

    Place the masses and holder on the spring so as to allow their weight to compress on the spring. Measure the distance that the spring is compressed. By Hooke's law, the force exerted by the spring is equal to -kx. This force is now equal, but opposite to, the weight of the masses and holder.

    So: kx=mg Then: k=mg/x.

  • Method 2:

    Attach the spring and car assembly to the end of the air track and load the smaller car into the spring, engaging the release mechanism. Measure the displacement of the end of the spring, (x). Release the small car and measure its velocity by timing it through a distance. Since mechanical energy is conserved, the elastic potential energy of the compressed spring is equal to the kinetic energy of the small car.

    So: 1/2kx2=1/2mv2 Then: k=mv2/x2.


Equipment:

  • Timer
  • Meter Stick
  • Air Track
  • Gliders w/ spring attachment
  • Weight Holder
  • Weights