The Law of Conservation of Momentum states that in a closed system, the total momentum of masses before and after their collision is constant-momentum, which is conserved. This states that when two things collide the sum of the momentum will be the same before the collision as after. This law also states that the magnitude of two colliding objects’ momenta must be equal in order for the vector sum of the opposing momenta to equal zero.

This equation can be seen as


In this particular experiment the Law of Conservation of Momentum was verified. The Law of Conservation of Momentum states that the magnitude of the the colliding objects should allow for the opposing momenta to equal zero. In the case of this experiment the percentage difference of the trials for the most part remained under 10%. This number taken into account with different sources of human error allows for the experiment to be verified. For example, the percentage error of the second trial was 1.32% which is very close to the required momenta as stated in the law.


In this experiment several sources of error were possible. One source of error for example is that the scale may not have been exact.  This source of error could lead to a miscalculation of the final momentum as well as the percentage error. Another source of error which could arise is the dynamics track could be off balance. This causes a variation in the velocity of the two objects. Another source of error is a potentially faulty motion sensor which does not make the proper recordings. This source of error could also help lead to issues when trying to determine the velocity as well as momentum and percentage error. These sources of error are all able to contribute to malfunctioning in proving the Law of Conservation of Momentum.

A closed system is defined as when the masses in an experiment do not have an external force acting upon them. The set up of these carts was not necessarily the best example of a closed system however. In this experiment external forces such as applied force and friction are used on the carts. An applied force, which in this experiment is the plunger is used in order for the carts to be able to begin their motion. Also while on the cart, the external force of friction is seen as acting on the cart while it is in motion in order to slow it down. Therefore, with these external forces acting on the carts this is not a very good example of a closed system.

Leave a Reply

1 Comment on "Law of Conservation of Momentum Lab Answers"

Sort by:   newest | oldest | most voted
Buzwiz L.

It can be proved theoretically that the total linear momentum in an isolated system is conserved.