Question about Centripetal Force

In summary: The centrifugal force should not be considered as some usual force like electrostatic force or gravity, rather, it refers to the composition of some forces. When it rotates faster, the velocity increases, which leads to an increase in the centrifugal force. This force needs to be balanced by the tension in the string in order to keep the mass in a circular orbit. Therefore, the string will stretch and the radius of rotation will increase.
  • #1
theintarnets
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So in a physics experiment, we used a motor to rotate a mass connected to a spring by a string and pulley until it's radius of rotation increased to a certain point. My question is, why did rotating it faster increase the radius of rotation? Centripetal force pulls objects inward, but the mass looked like it was being pulled outward the faster it rotated. I have a feeling that it has to do with the magnitude and direction of velocity as it increased, but I'm not sure. When the mass was being pulled outward, it also pulled on the string and caused the spring to stretch, but I don't understand why that happened either. Can someone explain this to me please?

The picture I have shows the setup before removing the hanging mass and pulley on the left and before rotating. When you remove the hanging weights, the spring pulls the suspended mass towards itself, I guess because the tension in the string is reduced and can no longer counter the tension in the spring.
 

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  • #2
The centrifugal force should not be considered as some usual force like electrostatic force or gravity, rather, it refers to the composition of some forces.
When it rotates faster, the velocity increases. In this case, we need to increase the centrifugal force to stop it from flying away. Actually,the radial velocity tends to pull the string outwards until the tension is strong enough to keep it in a circular orbit.


theintarnets said:
So in a physics experiment, we used a motor to rotate a mass connected to a spring by a string and pulley until it's radius of rotation increased to a certain point. My question is, why did rotating it faster increase the radius of rotation? Centripetal force pulls objects inward, but the mass looked like it was being pulled outward the faster it rotated. I have a feeling that it has to do with the magnitude and direction of velocity as it increased, but I'm not sure. When the mass was being pulled outward, it also pulled on the string and caused the spring to stretch, but I don't understand why that happened either. Can someone explain this to me please?

The picture I have shows the setup before removing the hanging mass and pulley on the left and before rotating. When you remove the hanging weights, the spring pulls the suspended mass towards itself, I guess because the tension in the string is reduced and can no longer counter the tension in the spring.
 

1. What is centripetal force?

Centripetal force is the force that acts on an object moving in a circular path, always pointing towards the center of the circle. It is responsible for keeping the object in its circular motion and preventing it from flying off tangent to the circle.

2. How is centripetal force related to centrifugal force?

Centripetal force and centrifugal force are two forces that act on an object in circular motion. Centripetal force pulls the object towards the center of the circle, while centrifugal force is the equal and opposite reaction force that appears to push the object away from the center. In reality, centrifugal force is a fictitious force that only appears due to the object's inertia.

3. What is the formula for calculating centripetal force?

The formula for centripetal force is F = (mv^2)/r, where F is the centripetal force, m is the mass of the object, v is the velocity, and r is the radius of the circle.

4. How does centripetal force change with the mass and velocity of the object?

As per the formula, centripetal force is directly proportional to the mass and the square of the velocity of the object. This means that if the mass or velocity of the object increases, the centripetal force required to keep it in circular motion also increases.

5. What are some real-life examples of centripetal force?

Some common examples of centripetal force include the Moon orbiting around the Earth, a car turning on a curved road, and a satellite orbiting around a planet. Other examples include a ball tied to a string being swung around and a clothes dryer spinning clothes in a circular motion.

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