Question

Frustated about problem. Uniform circular motion, the net force should be towards center, but in this case it does not. The problem involves a vertical circle (also called loop the loop)

Answer 1

I am looking at this problem here
http://physics.stackexchange.com/questions/77341/normal-force-of-loop-the-loop-at-the-side-of-the-circle/142085#142085

on the side of a vertical circle, the net force does not point towards center

Answer 2

@ProfBrainstorm @Zale101

Answer 3

the problem is
mass of 20 kg is moving in a vertical circle with radius 5 m, at a constant speed of 10 m/s

Answer 4

this website also says that the centripetal force on the side is N
https://answers.yahoo.com/question/index?qid=20110208155938AAUsxgW

Answer 5

Bear in mind that you are dealing with vector quantities.
The weight is acting vertically downwards, whereas when the car is at the side of the loop, the normal force is acting horizontally.
So the force of gravity is not relevant at that point.

Answer 6

this is a vertical circle so the weight is relevant

Answer 7

i think

Answer 8

not when you want to calculate the normal force when the car is at the side of the loop

Answer 9

ok, that website was just for reference. but my main question, how come the net force does not point towards center?

Answer 10

you just need to consider the horizontal components of any forces involved, but gravity does not act in the horizontal direction

Answer 11

i understand that, but my physics book says that in uniform circular motion with a given mass , the net force points towards center

Answer 12

you are looking at the motion as a whole, which in this case will be complicated by gravity, and there will need to be other forces provided to counteract gravity to maintain the motion at constant speed
That is why the question is careful to ask you to consider the situation at the particular point where those complications can be ignored

Answer 13

is it true that in uniform circular motion, the net force is always pointed towards center?

Answer 14

yes, that is true

Answer 15

if you scroll down on this page http://physics.stackexchange.com/questions/77341/normal-force-of-loop-the-loop-at-the-side-of-the-circle/142085#142085

is the last submission true ? the last post

Answer 16

no, because as i mentioned above, some other lateral force would have to be provided to cancel the effect of gravity to keep the body moving at constant speed, this force has been left out of your equation for Fnet

Answer 17

but the question is put in such a way that you don't need to worry about that !

Answer 18

because at the moment you are interested in, the force of gravity and any compensating lateral forces are perpendicular to the centripetal force

Answer 19

what force counteract gravity, i dont see any other forces

Answer 20

lol

Answer 21

what force can counteract gravity*

Answer 22

im not particularly interested in finding the normal force. im trying to understand this as a whole. the equations don't add up

Answer 23

that depends on the design of the loop the loop machine
some means would have to be provided to maintain uniform motion