A collision is an impact between two or more moving objects that violently strike each other. The amount of momentum of the objects reflect the outcome of the crash. The 'Conservation of Momentum' states that the total momentum before an event is equal to the total momentum after an event. This is why the higher the speed of a car in a crash, the more damage it will do.

Aim 🍙

To investigate whether total momentum is conserved during a collision.

Method 🍼 and Materials🎐

- Two dynamic trolleys

- Electronic balance

- Meter ruler

- ruler

- Several 1KG masses to add to the trolleys

- 2 x Rubber bands

- Level bench top

- Piece of A4 paper

- Masking tape

1) Attach the piece of A4 paper to the bench top with masking tape. Rule two parallel lines on the paper, 20 cm apart.

2) Link the two trolleys with the rubber bands.

3) Pull the trolleys apart and hold them with their front ends on the two lines.

4) Release the trolleys. The trolleys will accelerate towards each other and collide at the same time. How far the trolleys travel travel in a given time is proportional to their relative velocities.

Determine where the trolleys collide and mark the collision point on the paper.

5) Measure the distance from one line to the collision point, and the same for the other one. Because the trollies collide at the same time, there is no need to measure the time because distances are proportional to the collisions.

6) Add various masses to one (or both) of the trollies and repeat the experiment. Test five different weight combinations


Mass of the trolley = 300g

Weights = 50g each

m1 = 300g + two weights

m1 = 300g + 100g

= 400g

D = 20

Momentum = (m1 x d1) - (m2 x d2)

(0.400g x 0.20) - (0.300 x 0.20)

= 0.02

The momentum of this crash was 0.02