Rotational Motion FInding the total ENergy

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Homework Help Overview

The discussion revolves around a problem in rotational motion involving a ball rolling off a table and down a ramp. The original poster attempts to calculate the final velocity of the ball by considering various forms of energy, including gravitational potential energy, linear kinetic energy, and rotational kinetic energy.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of different energy types and question whether the sum of initial energies equals the sum of final energies. The original poster seeks confirmation of their final velocity calculation and the validity of their energy conservation assumption.

Discussion Status

Some participants provide feedback on the calculations, with one confirming the final velocity is reasonable based on their own rounding. Another participant offers insights into the rotational kinetic energy formula and emphasizes the importance of the rolling condition, suggesting that energy conservation is a valid assumption for this scenario.

Contextual Notes

The original poster expresses urgency for assistance, indicating a time constraint in their homework process.

Schu
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Particulars:
ball has a radius of 2.5 cm a mass of .125 and is rolling across a table with a speed of .547 m/s, this table is 1.04 m off the ground. It rolls to the edge and down a ramp How fast will it be rolling across the floor?

First I found the Gravitational Potential Energy: Ep=mgh
Initial of 1.2753 FInal = 0

THen the Linear Kinetic ENergy : 1/2 mv^2
Initial .0187005625 FInal .0625v^2

Elastic Potential Energy: .5k(delta)x^2
0 0

Rotational Kinetic Energy: 1/5mv^2
initial .007480225 FInal .025v^2

Now I need to bring them all togther and solve the final velocity.

Is the Sum of the inital energy's = to the SUM of the final energy's?
If that's true then 1.30148075 = .0875v^2
so v = 3.85 m/s
Is that at all right?? :confused:
 
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I need help ASAP

Is anyone out there?

I would appreciate the help :confused:
 
Looks ok to me. (I got 3.86 m/s, by rounding off)
 
rotational KE

I didn't check your arithmetic, but I have some comments.
Schu said:
Rotational Kinetic Energy: 1/5mv^2
The rotational KE is [itex]{KE}_{rot} = 1/2 I \omega^2[/itex].

You will also need the "rolling condition": [itex]V = \omega R[/itex].
Is the Sum of the inital energy's = to the SUM of the final energy's?
Yes, if you assume energy is conserved, which seems reasonable for this problem.
 

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