Conversation of momentum PDF

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Conservation of Momentum

Name: Chel, May Myet Partner’s name: Leo Leanza PHY 116 – 13725 Lab number 10 – Conservation of Momentum Date: 11/17/2017 Instructor’s name: Mihaela Drenscko

Objective: The objective of this experiment was to verify the conservation of momentum in the collision of two air track gliders. In this experiment the theory of the conservation of momentum is tested by varying the mass and velocity of two colliding objects moving of a frictionless surface and their momentums determined before and after they collide. The momentum of the object was also measured under coupling conditions, where the two objects were allowed to stick together. Principles/laws tested and used: The linear momentum (P) of an object can be defined as the product of that objects mass (m) and velocity (V). It is a quantity which has both magnitude and direction, which is in the same direction as its velocity. Therefore, momentum can be represented by the equation P = mV, which indicates that if two objects are of equal mass the object with the greater velocity will have the greater momentum. However, if two objects are moving at equal velocity, the object with the greater mass will have the greater momentum. Momentum is a conserved quantity, this means when two objects collide, if there is no external force acting on them, the total momentum before the collision will be equal to the total momentum after the collision.

If the two objects stick together after the collision, some initial kinetic energy will be transformed to some other form of energy and kinetic energy will not be conserved. However, the momentum will still be conserved, this collision is called inelastic collision. Discussion and Errors: Since linear momentum is a conserved quantity, the linear momentum of the system of colliding air gliders is expected to be the same before and after the two air gliders collide. Changing the mass and velocities of the objects is not expected to affect the total momentum of the system under elastic or inelastic conditions. For condition 1 where both masses are equal, the total momentum before and after the collision had a difference of 19%. This is a relatively low difference which may have been caused by some external interference or errors which occurred during the experiment. Conditions 2 (114%) and 3 (150%) had higher differences between the momentum values, this may have been due to an increase in the mass of the objects which in turn magnified the errors which also affected condition 1. We can therefore assume that momentum was conserved for these conditions since the total momentum before and after th4e collision are close to each other. Condition 4 produced an unusually high difference (200%) in the total momentum. Although both objects move in opposite directions the total momentum of the system should have still be conserved, however these results indicate that the momentum was not conserved. We must therefore reject these results which may have resulted from a gross error in the reading of the photo gate when determining the velocity of the air gliders. Condition 5 was conducted as an inelastic collision, where the two objects remained attached after collision. The difference between the total momentum before and after the collision was then 46.9%. This is a relatively small difference which may have been caused by errors which occurred during the experiment. Some errors which may have influenced the results include, systematic errors associated with the instruments (air track and photo gate), gross errors in reading the time from the photo gate, air resistance. If the air track was not leveled it may have also influenced the results. Conclusion:

It can be concluded that when objects of a similar mass collide the kinetic energy of the system before the collision is equal to the kinetic energy of the system after collision. We can therefore conclude that the total momentum of the system was conserved as expected for an inelastic collision.

Apparatus:     

Linear air-track and air-track kit Two photo gate timers Variable air supply and hose Two gliders Electronic balance

Computations: Computations are in the data sheet. Questions: 1. There were small differences in the momentum for the collisions, these differences may have been due to a combination of errors mentioned in the discussion. Condition 4 had to be rejected due to its large error which may have been caused by a gross error in the reading of the photo gate.

2. If the air track was tilted during the experiment the momentum of the system would not have been conserved. This is because an external force (gravity) would be acting on the gliders causing them to continuously accelerate after the collision....