Forces involved in circular motion

[scottnobles]

Homework Statement

hey, i was looking at an explanation in a textbook where it says a ball on the end of a string is swung horizontally in circular motion. There is a centripetal acceleration therefore tension acts as the centripetal force and acts along the radius of the circular path. What i want to know is that Newtons third law states that every action has an opposite and equal reaction. So what is the reaction force of the tension acting on the string?

Homework Equations

F=mv^2/r

The Attempt at a Solution

I can't seem to be able to figure out what it is but i think mass would not be the reaction force because mass is a scaler and has no direction. The other explanation would be centrifugal force but isn't centrifugal force a reaction force of centripetal force? which is what I am trying to find? This is why I am a little confused.

 

[rl.bhat]

Moon rotates around the Earth because the gravitational force of the Earth pulls the moon towards it. It is action of Earth on moon. Because of the initial horizontal velocity the moon is no falling towards the earth. As as reaction moon pulls the earth. Tides are the evidence of that.

 

[tomcue]

I can understand your confusion about the forces involved in circular motion. Let me help clarify this for you.

Firstly, you are correct in your understanding that Newton's third law states that every action has an opposite and equal reaction. In the case of a ball on a string being swung in circular motion, the tension in the string provides the centripetal force that keeps the ball moving in a circular path. This is the action force.

Now, according to Newton's third law, there must be an equal and opposite reaction force. In this case, the reaction force is provided by the ball itself. As the string pulls on the ball, the ball exerts an equal and opposite force on the string. This reaction force is what allows the string to remain taut and continue to provide the centripetal force.

You are correct that mass is a scalar quantity and does not have a direction. However, in this case, the reaction force is not necessarily a vector quantity like force. It is simply the equal and opposite force to the tension in the string, which is provided by the ball.

As for centrifugal force, it is not a reaction force to the centripetal force. Centrifugal force is a fictitious force that arises due to the fact that we are observing the motion from a non-inertial reference frame. It is not a real force, but rather a mathematical concept that helps us understand the motion of objects in circular motion.

In summary, the reaction force to the tension in the string is provided by the ball itself, and it is equal and opposite in direction to the tension force. I hope this helps clarify your understanding of the forces involved in circular motion.