Direction of friction in a yoyo rolling on an inclined plane

AI Thread Summary
Friction acts downwards on a yoyo rolling down an inclined plane to prevent slipping, as the yoyo would rotate in the opposite direction without friction. If there were no friction, the yoyo would rotate upwards, causing the contact point to slip upwards on the incline. To counteract this tendency, friction must act downwards. The difference in perimeter between the yoyo and the cylinder affects the distance traveled per revolution, necessitating friction to maintain rolling motion. The discussion also considers how the direction of the applied force affects the frictional force's direction.
dahoom102
Messages
12
Reaction score
2
Homework Statement
In this problem why is the friction directed downwards not upwards? Shouldn't the velocity of the point of contact with the ground be zero and therefore mgsin = fs ? All of the problems i studied the friction was in the upward direction i just wanna know why is it different here.
Relevant Equations
F.B.D
Mgsin
fs
Screenshot_20210304-190909_Drive.jpg
 
Physics news on Phys.org
dahoom102 said:
In this problem why is the friction directed downwards not upwards?
If there was no friction, which way would the yoyo rotate? And, therefore, which way would the contact point of the yoyo tend to slip on the surface of the incline? Which way must friction act to prevent such slipping?
 
The perimeter of the yo-yo is bigger than the perimeter of the cylinder around which the syring is wrapped.
For one revolution, the traveled distance and the length of string are different: one must yield.

Please, see:
https://www.physicsforums.com/insights/explaining-rolling-motion/

:cool:
 
dahoom102 said:
In this problem why is the friction directed downwards not upwards?
Take moments about the centre of the yoyo. What does that tell you about F and fs?
What if the string were wound the other way around, so that F is applied above the centre?
 
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
Back
Top