Energy, Power, Work related question

AI Thread Summary
The discussion revolves around a physics problem involving a pitcher rotating a 0.25kg ball in a vertical circular path before release. Key calculations involve kinetic energy (KE) and potential energy (PE) to determine the speed of the ball at release. The initial equations provided are correct, but there is a mention of the work done by the pitcher, which is crucial for accurate calculations. The conversation highlights the importance of considering all forces and energy transformations in the problem. Overall, the focus is on clarifying the calculations to find the correct speed upon release.
alevis
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This isn't the actual problem given in the assignment. I've twisted it a bit because I want to see were I specifically go wrong in my calculations.
1. A pitcher rotates a 0.25kg ball around a vertcal circular path of radius 0.6m before releasing it. The pitcher exerts a 50N force directed parallel to the motion of the ball around the complete circular path. The speed of the ball at the top of the circle is 20m/s. If the ball is released at the bottom of the circle, what is the speed upon release?



2. KE = 1/2mv^2
PE = mgh
Energy at top = Energy at bottom.
1/2mvi^2+mgh = 1/2mvf^2+mgh.


3.vf = sqrt (1/2mvi^2+mgh-mgh)/m
 
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Welcome to PF!

Hi alevis! Welcome to PF! :smile:
alevis said:
A pitcher rotates a 0.25kg ball around a vertcal circular path of radius 0.6m before releasing it. The pitcher exerts a 50N force directed parallel to the motion of the ball around the complete circular path. The speed of the ball at the top of the circle is 20m/s. If the ball is released at the bottom of the circle, what is the speed upon release?

3.vf = sqrt (1/2mvi^2+mgh-mgh)/m

What about the work done by the pitcher? :wink:

(and you're missing a 2)
 
thanks alot
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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