SHM

22 Answers

1
skygirl ·

we can conservve energy about point of contact since no slipping there..

so

U = 1/2 k x2 + 1/2 k x2 + 1/2 I ω2

= 1/2 k x2 + 1/2 k x2 + 1/2 (mR2 + 2/5 R2)ω2

diffrentiating both side,

0 = 2kx v + 7/5m v a

=> a = -(10k/7m) x

so, ω2 = (10k/7m)

bus [1]

24
eureka123 ·

thanx sir..................sorry it came a bit toooo late.....

1
skygirl ·

oh shit.

it was a solid 'cylinder'... n i constantly read it solid 'sphere'...

dats y told diptosh n all incorrect.. [2] [2] [2]

I AM TOOOOO SORRY TO U ALL N MOST IMPORATNTLY MYSELF (for not able to materialise successfully my N-Y resolution [2] [2] .... bhaiya i will 'try' harder to avoid these... [2])

62
Lokesh Verma ·

sky, your mistake is that you have taken I corresponding to a sphere.. here it is a cyllinder...

Kep in mind that these misakes will kill all ur preparations... You have to not make these mistakes.... other mistakes are allowed...

62
Lokesh Verma ·

the total energy of the system is constant and then find its derivative..

E=1/2k(2x)2+1/2k(2x)2+1/2mv2+1/2 Icm(v/r)2

I=1/2Mr2

v=dx/dt

E=k(2x)2 + 3/4mv2
E=k(2x)2 + 3/4m (dx/dt)2
now take dE/dt=0

8kx(dx/dt)+3/2m(dx/dt) d2x/dt2 = 0

8kx+3/2md2x/dt2=0

d2x/dt2=-16k/3m x

hence 2pi √3m/16k

pi √3m/4k

1
skygirl ·

energy eqn ??

i am correct..

i have taken for point of contact..

u took it for com.

3
msp ·

dat x and v relation i think so leave it if i was wrong...

1
skygirl ·

tell jaldi jaldi ...

1
skygirl ·

tell jaldi jaldi ...

1
skygirl ·

wat ?

3
msp ·

oops sky u made a mistake

3
msp ·

Hint:

the total energy of the system is constant and then find its derivative..

E=1/2k(2x)2+1/2k(2x)2+1/2mv2c+1/Icm(vc/r)2

and x is the distance moved by com at a particular instant

1
skygirl ·

ω = √10k/7m

time period = 2Î √7m/10k

1
skygirl ·

n no u are not correct :P

1
skygirl ·

oops i am sorry...

u are correct only ..

1
skygirl ·

ans is not that wat u gave diptosh..

its pi√3m/2k

1
skygirl ·

hmm.. irodov stuff...

62
Lokesh Verma ·

it is on the top and i think this is from Irodov.. a standard problem which is not very difficult...

I think the expression sankara gave is correct.. you just need to do a bit more to that

ie find the relation between v and x!

1
Diptosh ·

What's wrong with the springs at the top ?

Ans : pi √(3m/4k)

24
eureka123 ·

Top..........maybe!!!!!!!

3
msp ·

Assume that the springs r at the topmost point...

1
Philip Calvert ·

hey those springs in the middle or on the top ?

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