Two beads of mass m each are positioned at the top of a frictionless hoop

How to find the given value?
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17 Replies
iTeachChem Helper
@Gyro Gearloose
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Opt
Opt4mo ago
Normal force has vertical component
Gamertug
Gamertug4mo ago
it applies force up after the center is crossed?
Opt
Opt4mo ago
No, at all point. Ring applies a normal force outward equivalent to mv²/r, and that has a vertical component at all times
SirLancelotDuLac
Apply energy conservation and find centripetal and hence normal, and use that to find vertical comp. of resultant.
Gamertug
Gamertug4mo ago
wouldnt it apply downward force if above center
SirLancelotDuLac
The normal is pushing the beads inwards, so by 3rd law, the beads push ring radially outward.
Gamertug
Gamertug4mo ago
how inwards?
SirLancelotDuLac
Something like this
No description
SirLancelotDuLac
The centripetal force of the beads is inwards correct? Thus, the tendency of normal by the ring would be to push the beads radially inwards. Thus, the normal on ring by beads is opposite and radially outwards. (When the mgcos(theta) component is not able to provide centripetal, as theta increases meaning this would decrease while the velocity and hence, centripetal increases.)
Gamertug
Gamertug4mo ago
i thought the weight by beads would put a force on the ring and hence the ring would push it beads outward
SirLancelotDuLac
But they are moving in a circular path right? So there must be centripetal.
Gamertug
Gamertug4mo ago
and what abt the weight by beads on the ring
SirLancelotDuLac
Initially the mgcos(theta) component is too much and you are right, normal is outwards. But velocity increases as beads come down and theta increases. So mgcos(theta) is not able to provide appropriate centripetal In which case the normal force steps in to provide the same, in radially inwards direction.
Percy
PercyOP4mo ago
makes sense Thank you so much +solved @SirLancelotDuLac @Opt
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