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Question
A person drops a coin. Describe the path of the coin as seen by the person if he is in
- a car moving at constant velocity and
- in a free falling elevator.
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Solution
When the person drops the coin, the path of the coin as seen by the person is:
(a)
- When a person drops a coin inside a car moving at constant velocity, the coin appears to fall straight down from the person’s point of view.
- This is because both the person and the coin are moving forward with the same velocity as the car.
- There is no additional force acting on the coin in the horizontal direction, so the coin retains its forward motion and lands directly below the point from which it was dropped.
- This situation reflects the principle of relative motion and supports Newton’s first law an object in motion continues in motion unless acted upon by an external force.
(b)
- In a free falling elevator, both the person and the coin are accelerating downward at the same rate due to gravity.
- When the person drops the coin, from their point of view, it appears to hover, float in the air, or fall very slowly.
- The person and the coin are both in free fall together, so there is no relative acceleration.
- This provides the sensation of weightlessness, similar to what astronauts experience in orbit.
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