Go Back   Physics Help Forum > High School and Pre-University Physics Help > Periodic and Circular Motion

Periodic and Circular Motion Periodic and Circular Motion Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Aug 19th 2017, 02:12 AM   #1
Junior Member
 
Join Date: Aug 2017
Posts: 2
Circular Motion Question.

A particle of mass m oscillates along arc AB on the inside of a smooth circular hoop of radius 'a' fixed in a vertical. The force on the hoop at any point is : ?
(a) k/a (b) k/3a (c) 2k/a (d) 3k/a
CosmicC is offline   Reply With Quote
Old Aug 19th 2017, 06:00 AM   #2
Senior Member
 
Join Date: Aug 2010
Posts: 321
The downward gravitational force on the object at any time is, of course, mg. The object does not go downward because the hoop is applying a force on it. That force is equal to the component of gravitational force perpendicular to the hoop. Let $\displaystyle \theta$ be the angle the line from the center of the hoop makes with the vertical. The component of gravitational force perpendicular to the hoop is $\displaystyle mg cos(\theta)$ and is also the force the object applies to the hoop. That does not appear to be any of the options you give. In particular, that force is not a constant- it is greatest at the bottom and least at the end points of the arc.
HallsofIvy is offline   Reply With Quote
Old Aug 19th 2017, 07:30 AM   #3
Junior Member
 
Join Date: Aug 2017
Posts: 2
Answer.

Originally Posted by HallsofIvy View Post
The downward gravitational force on the object at any time is, of course, mg. The object does not go downward because the hoop is applying a force on it. That force is equal to the component of gravitational force perpendicular to the hoop. Let $\displaystyle \theta$ be the angle the line from the center of the hoop makes with the vertical. The component of gravitational force perpendicular to the hoop is $\displaystyle mg cos(\theta)$ and is also the force the object applies to the hoop. That does not appear to be any of the options you give. In particular, that force is not a constant- it is greatest at the bottom and least at the end points of the arc.


I managed to solve it when i tried again. Check it out.
CosmicC is offline   Reply With Quote
Old Aug 20th 2017, 09:14 AM   #4
Pmb
Physics Team
 
Join Date: Apr 2009
Location: Boston's North Shore
Posts: 1,526
Originally Posted by HallsofIvy View Post
The downward gravitational force on the object at any time is, of course, mg. The object does not go downward because the hoop is applying a force on it. That force is equal to the component of gravitational force perpendicular to the hoop. Let $\displaystyle \theta$ be the angle the line from the center of the hoop makes with the vertical. The component of gravitational force perpendicular to the hoop is $\displaystyle mg cos(\theta)$ and is also the force the object applies to the hoop. That does not appear to be any of the options you give. In particular, that force is not a constant- it is greatest at the bottom and least at the end points of the arc.

Posting full answers to homework problems violates forum rules. Please see:

Must read before posting a problem : please show your attempt!
The Helpers and the staff of the forum have agreed that they won't give a full answer to a problem posted with no attempt (except maybe in some cases). The Helpers are here to help you to understand your weaknesses by going through the asked questions with you and not here to solve your physics problems.
It is imperative to show an attempt to a problem. If you don't know how to start, say it. Helpers will give you a push in the right direction.
Pmb is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Periodic and Circular Motion

Tags
circular, force, mechanics, motion, question



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Another circular motion question punintentional Periodic and Circular Motion 2 Apr 2nd 2017 01:48 AM
Circular motion question punintentional Periodic and Circular Motion 1 Mar 30th 2017 07:51 AM
about circular motion roccoo Kinematics and Dynamics 4 Feb 26th 2011 10:52 AM
[SOLVED] Circular motion question xtheunknown0 Kinematics and Dynamics 1 Jan 15th 2011 11:23 PM
circular motion physics Kinematics and Dynamics 1 Sep 29th 2009 02:17 AM


Facebook Twitter Google+ RSS Feed