Circular Motion: Find Tension at Top of 1.11kg Disc

In summary, the problem involves finding the tension at the top of a vertical circle with a given mass, radius, and speed. The solution involves using the equation for centripetal force and recognizing that at the top of the circle, the forces acting are the normal reaction and the tension, with the resultant being the centripetal force. Drawing a free body diagram and using the equation Sum F = m*a can help in understanding the problem.
  • #1
electricheart
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Homework Statement



A 1.11 kg disc is whirled in a vertical circle with radius 0.680m about a fixed point. Find the tension at the top if the speed at the top is 8.76 m/s.

Homework Equations



F= ma
F= m* Acp
Acp= m(w^2*r)

3. The Attempt at a Solution
I figured centripetal force was acting on the mass so I used the equation w=v/r to find omega(w), then I found the Acp. But that answer is incorrect. If at the top of a circle will the tension be the same Acp.
 
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  • #2
At the top of the circle, the forces acting are the normal reaction of the 1.11kg mass and the tension. Both acting downwards. The resultant of those two is the centripetal force mv2/r
 
  • #3
So F + M g = Acp.
Alright, thanks.
 
  • #4
Centripetal force is not really a force at all, it is a mass*acceleration term.

You will get a much better understanding of this problem (as opposed to simply getting an answer quickly) if you draw a free body diagram and write Sum F = m*a where you recognize that for a body in uniform circular motion, a = - r * omega^2 * er, a vector pointing towards the center of the circle.
 

What is circular motion?

Circular motion is the movement of an object along a circular path. This means that the object is constantly changing direction and always moving at a constant speed.

What is tension in circular motion?

Tension in circular motion refers to the force that is exerted on an object in order to keep it moving along a circular path. In other words, it is the force that prevents the object from flying off in a straight line.

How do you calculate tension in circular motion?

To calculate tension in circular motion, you need to know the mass of the object, the radius of the circular path, and the speed of the object. You can then use the formula T = m*v^2/r, where T is the tension, m is the mass, v is the speed, and r is the radius.

Why is finding the tension at the top of a disc important in circular motion?

Finding the tension at the top of a disc is important because it helps us understand the forces acting on the object as it moves along a circular path. It also allows us to calculate the minimum speed required for the object to maintain its circular motion without falling off the path.

What factors can affect the tension in circular motion?

The tension in circular motion can be affected by the mass of the object, the speed of the object, and the radius of the circular path. Any changes in these factors can result in a change in tension.

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