Physics project, looking for ideas?

Question

Im looking for ideas on a physics project involving a car that must carry an egg, only using the power of a droping 3kg mass. The car must go 10m then come to a stop before hitting a wall. If you have any ideas let me know

Answer 1

Mass is attaced to a cord which is passed over a pulley (or pulleys). The end of the cord is wound around one of the axels on your car.

The Ideal is to have the car accelerate by the weight dropping and unwinding from the axel. About half way to the wall the end of the cord is reached but since it is attached to the axel the forward momentum of the car would start to wind it back onto the axel. This would slow the car down as it approached the wall after the half way point.

Some type of ratchet which only let the car move in the forward direction would prevent the car from backing up once it slowed to a stop near the wall with the now re-elevated weight