A 0.21 kg ball on a string is whirled on a vertical circle at a constant speed. When the ball is at the three o'clock position, the tension is 18 N.
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(a) How does the magnitude of the centripetal force acting on the ball relate to each point on the circle? The magnitude is the same at each point on the circle.
The magnitude is not the same at each point on the circle.
There is insufficient information for a definitive answer.
Is the answer the magnitude is not the same at each point on the circle?
Yes, the answer is "The magnitude is not the same at each point on the circle."
Yes, the correct answer is that the magnitude of the centripetal force acting on the ball is not the same at each point on the circle.
To understand why, let's consider the forces acting on the ball when it is at different positions on the vertical circle:
1. At the topmost point (12 o'clock position): At this point, the tension in the string is responsible for providing the centripetal force to keep the ball moving in a circular path. Additionally, there is gravitational force acting downwards on the ball. These two forces must add up to provide the necessary centripetal force.
- Tension (upwards) + Weight (downwards) = Centripetal force
2. At the bottommost point (6 o'clock position): Here, the tension in the string is still responsible for providing the centripetal force, but the weight of the ball acts in the same direction as the tension, resulting in a larger overall force.
- Tension (downwards) + Weight (downwards) = Centripetal force
3. At the three o'clock position: The tension in the string is still responsible for providing the centripetal force, but the weight of the ball acts perpendicularly to the tension, making it reduce the effective force from tension alone.
- Tension (outwards) - Weight (downwards) = Centripetal force
Therefore, the magnitude of the centripetal force at each point on the circle is different due to the varying influence of the weight of the ball.