1. The Apparatus
Trolley 2
Trolley 1
Pin
Timer
Tape
Track
Cork

2. To verify the principle of conservation of momentum
Set up apparatus as in the diagram.
Adjust the track until the trolley runs at a steady speed.
Measure the mass of each trolley using a balance.
With trolley 2 stationary, give trolley 1 a gentle push. After collision the two vehicles coalesce and move off together.
Calculate the velocity before the collision and the velocity after the collision from the ticker tape.
Calculate the momentum of trolley 1 before the collision and the momentum of both trolleys after the collision. Momentum = mass x velocity.
Repeat several times, with different velocities and different masses.

3. Results
Mass of trolley 1
Mass of trolley 2
Initial speed
Final speed
Momentum before impact
Momentum after impact
Conclusion
The momentum before impact is equal to the momentum after impact.
Precautions
Slope the track to cancel the effect of gravity.
Dust the track to reduce the effect of friction.