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The following is part of a student's report on an experiment to verify the principle of conservation of momentum - Leaving Cert Physics - Question 1 - 2014
Question 1
The following is part of a student's report on an experiment to verify the principle of conservation of momentum. "I ensured that no external forces acted on body A... show full transcript
Worked Solution & Example Answer:The following is part of a student's report on an experiment to verify the principle of conservation of momentum - Leaving Cert Physics - Question 1 - 2014
Step 1
Draw a labelled diagram of the apparatus used in the experiment.
Answer
To draw a labelled diagram of the apparatus, depict the following:
- Two bodies (A and B) connected by a means of attachment (like a string) at the starting point of the track.
- A track for the bodies to move along.
- A timer or motion sensor near the light gate to measure the time taken for body A to pass through.
- Ensure to label each part of the diagram clearly.
Step 2
State what measurements the student took and how these measurements were used to calculate the velocities.
Answer
The measurements taken were:
- Masses of both bodies (325.1 g for body A and 349.8 g for body B).
- Velocity of body A before the collision (0.84 m s⁻¹).
- Time intervals for both bodies to pass through a light gate, measured using a timer or motion sensor. The velocity was calculated using the formula: ext{Velocity} = rac{ ext{Distance}}{ ext{Time}} where distance is the length of the card (or body) that is passing through the light gate.
Step 3
Using the recorded data, show how the experiment verifies the principle of conservation of momentum.
Answer
The principle of conservation of momentum states that the total momentum before the collision is equal to the total momentum after the collision. Using the recorded data:
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Momentum of body A before collision:
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Momentum of body B before collision is zero, as it is at rest:
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Total momentum before collision:
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Momentum of both bodies after the collision:
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Velocity after collision is given as 0.41 m/s:
There seems to be a slight difference, but it illustrates that momentum is conserved during the collision.
Step 4
What are the two forces that the student needs to take account of to ensure this?
Answer
The two forces that the student needs to account for are:
- Gravitational force acting on the bodies, which can affect their motion as they move along the track.
- Frictional force caused by the interaction of the bodies with the air and the surface of the track.
Step 5
Describe how the student reduced the effects of these forces.
Answer
To reduce the effects of these forces, the student could take the following actions:
- To minimize gravitational force effects, they can ensure the track is level and reduces any incline that could affect motion.
- To reduce friction, the student could use a smooth track and ensure that the bodies are streamlined to minimize air resistance. Placement of oil or a lubricant on the track can also help decrease friction.