Bouncing ring


A small body 'A' is fixed to the inside of a thin rigid hoop of radius R and mass equal to that of body 'A'. The hoop rolls without slipping over a horizontal plane. At the instant when the body is at lowermost position, the centre of the hoop moves with velocity v. For what values of v will the hoop move without bouncing?

12 Answers

19
Debotosh.. ·

use the concepts of rolling, along with the fact that the question is trying to say :" normal force of the small object never becomes zero" !

1
Unicorn--- Extinct!! ·

Can you explain a little more..:(

1
Unicorn--- Extinct!! ·

Just 27 views!!!!!![17]

62
Lokesh Verma ·

Draw the fbd at an angle theta..

Find the relation between the velocities... at an angle theta... (by energy conservation?)

Now try?

1
Unicorn--- Extinct!! ·

Got it sir!!
Using energy conservation, the answer comes out to be √8gr.
The maximum possibility for the ring to bounce off is when the body is at the topmost position. Hence we will equate centripetal force to weight.

66
kaymant ·

@iota.1
can you show how it is coming to be √8gR by energy conservation?

3
msp ·

N-mgcosθ=mva2/R

N≥0 and va2=2gR(1-cosθ)

mg(3-cosθ)≥0 minimum value is cosθ=1/3

minimum velocity is √4/3gR

66
kaymant ·

@msp
that's definitely not correct. There are quite a few mistakes. First specify the reference frame. Because w.r.t the ground, the particle A is not moving in a circle. Secondly, how did you get va2=2gR(1-cosθ)?

1
Unicorn--- Extinct!! ·


At this instant, 2mrcmω'2=2mg

Ei=12Ipω02

Ef=12I'pω'2+(2m)gr

I'p=6mr2

I got the answer using these equations.

1
Arshad ~Died~ ·

thats correct...good work.... :-)

1
Unicorn--- Extinct!! ·

@ Arshad- You sure??

1
Arshad ~Died~ ·

yes i have seen it many times....100% sure

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