How Fast Does the Rim of a Spinning Disk Travel?

AI Thread Summary
To determine the speed of a point on the rim of a spinning disk, the kinetic energy formula K=(1/2)*I*(ω^2) is used, where I is the moment of inertia and ω is the angular velocity. The moment of inertia for a thin disk is calculated as I=(1/2)*M*R^2. The user encounters difficulties in calculating the correct angular velocity and converting it to linear speed. There is a realization of a potential calculation error, prompting a reconsideration of the approach. The discussion highlights the importance of correctly applying formulas and unit conversions in physics problems.
Nitrag
Messages
11
Reaction score
0
Problem 13.30
A thin, 60.0g disk with a diameter of 7.00 cm rotates about an axis through its center with 0.240 J of kinetic energy. What is the speed of a point on the rim?

Homework Equations


m=.06kg
r=.035m
KE=.240J

The Attempt at a Solution



K=(1/2)*I*(w^2)
I=(1/2)*M*R^2

I'm using the formula above but I'm not getting the right answer. My numbers seem way to small. I eventually get w(omega) alone. Where do I go from here. Do i need to solve for the length to figure out rad/s then convert to m/s?

Perhaps I am approaching this wrong.
 
Physics news on Phys.org
Calculation error, sorry. Mods you can delete.
 

Thread 'Rolling without slipping on a curved surface'

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 .
View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »

Similar threads

Minimum initial speed to spin a particle around a disk (with gravity)
Replies
9
Views
2K
What is the final angular displacement of a disk hit by two masses?
Replies
3
Views
2K
Conservation of Energy and Angular Momentum in a Rotating Train-Disk System
Replies
30
Views
3K
Resultant linear acceleration at the rim of a disk
Replies
8
Views
8K
What is the net acceleration of the coin on a rotating disk?
Replies
2
Views
2K
Analyzing Rotational Motion of a Spinning Disk on a Horizontal Surface
Replies
15
Views
3K
What is the Time to Pivot the Rod with a Spinning Disk?
Replies
2
Views
1K
Why Do Moments Balance in a Faraday Disk but Not the Forces?
Replies
1
Views
1K
Moment of inertia of a set of spinning disks
Replies
25
Views
11K
Stuck in this question - 2 spinning disks brought together
Replies
22
Views
13K

Hot Threads

Recent Insights

Back
Top