3A60.24 Coupled Driven Carts Between Springs
Normal modes at resonant frequency
Two carts are connected by springs on a track. The coupled carts are then connected by a spring to one end of the track and by another spring to a driving motor that is controlled by a variac. At resonant frequency, the two carts appear to be out of phase and move in opposite directions.
-  Variac
-  DC motor
-  Cart
-  Cart track
-  Spring
-  String
-  250g mass
-  Small magnet
- Place the track on a horizontal platform near a power outlet.
- Connect a DC motor to the variac and position the motor such that students can see the rotation of the motor clearly.
- Add as many damping magnets to the cart bottoms as desired.
- Start with voltage at zero volts to begin.
- Increase the voltage carefully, be sure not to apply a voltage larger than 100 volts
- If cart oscillations are too strong, add more magnets to the undersides of the carts
- Connect the springs and the carts as shown on the image, if they are not already connected.
- Attach the spring to a screw at the end of the track.
- Connect the spring to a motor by a string.
- Turn on the variac and slowly increase the voltage.
- Put a 250g mass on top of the cart to increase the mass of the cart if necessary. Note that the mass of the cart is approximately 250g.
- PIRA 3A60.24
- Don't attempt this at home!
If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.