To check the validity of the principle of conservation for linear momentum using two dynamics
carts pushed apart from rest by an “Explosive” force.
Triple beam balance
2 dynamic Carts (one with spring)
2 loads (approximately 500g)
2 wooden blocks to fix the end position of the track
Marker or chalk
Procedure: 1. Place the grooved track on a flat surface, and place two wooden blocks on each side and
attach them by using two C-clamps, one on each side.
2. Make sure that the track is levelled.
3. Measure the mass of two dynamic carts and two loads on the triple beam balance and
record the mass.
4. Pushing the spring in of the cart, place both carts on the horizontal grooved track, facing
each other, such a way that the wheels of both the carts are on the grooves of the track.
5. Use weight to tap the tip of the spring cart, to release the “explosive” force and exert it
onto the other cart.
6. Observe the motion of the two carts.
7. Practice, doing this until you hear one simultaneous sound when both the carts hit the
wooden blocks placed on each side.
8. If you do not hear one sound, repeat steps 5-7; but change the starting position of the
carts so that they hit the wooden blocks at the same time.
9. Measure and record the displacement of each cart travelled; make sure one cart will
have negative displacement.
10. Perform several trials for accurate results.
11. Repeat steps 4-10 again by placing a 500g mass on Cart A; by placing a 500g mass on Cart
B, and by placing a mass of 500g on Cart A and Cart B. Observation
m A 0.5002KG and additional load for cart A= 0.5024KG
m B 0.4781KG and additional load for Cart B = 0.5012KG
Displacement of Cart A is positive and since cart B is travelling in opposite direction;
displacement of Cart B is negative.
Total Change Total Change in
mass of in mass distance %
Sequence Description A distanc m A d A of B of B MB× d B Error
m A e of A M B dB(m)
(KG) dA(m) (KG)
1 ‘A’ and ‘B’ 0.5002 0.43 0.2151 0.478 -0.44 -0.2104 -1.0223 2.23
2 ‘A’ loaded 1.0026 0.29 0.2908 0.478 -0.58 -0.2773 -1.0487 4.87
3 ‘B’ loaded 0.5002 0.56 0.2801 0.979 -0.31 -0.3036 -0.9226 7.74