Calculating Total Energy and Speed of a Ball on a Thread

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Homework Help Overview

The problem involves a solid rubber ball attached to a thread, swung in a vertical circle. Participants are tasked with calculating the total energy, speed at various points, tension in the thread, and the horizontal distance traveled before hitting the floor, using gravitational potential energy as a reference point.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of potential energy and kinetic energy in calculating total energy. Some suggest using equations related to energy conservation, while others question the initial length of the thread and its implications. There are attempts to clarify the relationship between energy at different points in the circle.

Discussion Status

The discussion is active, with participants exploring various approaches to the problem. Some guidance has been offered regarding the need to consider both potential and kinetic energy, as well as the application of Newton's laws for tension calculations. Multiple interpretations of the problem setup are being examined.

Contextual Notes

There is a noted confusion regarding the length of the thread, which was initially stated as 0.0 meters but later corrected to 0.80 meters. Participants are also reminded to show their work in the forum.

Baumeister41
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I need with a problem...A 0.10 kilogram solid rubber ball is attached to the end of an 0.0 meter length of light thread. The ball is swung in a vertical circle. point P, the lowest point of the circle, is 0.20 meter above the floor. The speed of the ball at the top of the circle is 6.0 meters per second, and the total energy is kept constant.
a)Determine the total energy of the ball, using the floor as the zero point for gravitational potential energy.

b)Determine the speed of the ball at point P, the lowest point of the circle

c)Determine the tension of the thread at...
i. the top of the circle
ii. the bottom of the circle

The ball only reaches the top of the circle once before the thread breaks when the bal is at the lowest point of the circle.
d)Determine the horizontal distance that the ball travels before hitting the floor



I'm not sure where to begin.


If anyone can help me it would be great!
 
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The length of the thread is 0.0 m?

You must show some work in the Homework forums. Can you think of anything useful in approaching this problem (relevant equations, etc)?
 
Last edited:
sry.im new to all of this stuff. the length of thread is 0.80 meters. well for part A i was Thinking PE=m*g*h because it said Potential energy. I get . Part B i think you do .5*m*v^2 = mgh and solve for the velocity. The for C the tension at the top is 0 or (m*g), not to sure on that one. D i can figure out using a kinematic equation
 
For a), you do need to consider the gravitational potential energy. But the ball is moving, so you need to consider the kinetic energy as well to get the total energy.

For b), since the energy remains constant, the energy at the top of the circle must equal the energy at the bottom of the circle. Since the ball is now closer to the floor, the relation between the potential and kinetic energies change. So just write out the terms for each.

For c), use the idea of a centripetal force with Newton's second law.

For d), yes, you can use kinematics to find the distance.
 
thank you very much. that was very helpful
 

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