not getting the answer plz help!!!

when released ,the mass 2m falls a distance x before the limp string becomes taut.thereafter both the mass on the left rise with the same speed.what is the final speed.

i have applied impulse momentum theoram.but not gettin te final answer

6 Answers

1
Little Angel ·

We can use the concept of work energy theorm .

Work doen by gravity and work done by tensions = change in K.E
initial velocity must be zero, final we have to calculate.

1
decoder ·

but here tension will be an impulsive force .

1
decoder ·

someone plz help

3
iitimcomin ·

g/3 = accn until it becomes taut ...

v^2 = 2(g/3)x

v(i)=√(2gx/3)

now a sudden impulsive force [tnsion] acts .. say T for time dt

for block just rising

Tdt = mv [for lowermost block][neglecting mg and all dat ]

(T1-T)dt = mv - mv(i)

-T1dt = 2mv - 2mv(i)

add all three

4mv -3mv(i) = 0

v =(3/4)v(i) ..... but v(i) value from before

3
iitimcomin ·

assumin the right block is not on the floor when the left string becomes taut ........

[and for clarification T1 is the implusive tension developed in the second string due to the first]

1
decoder ·

thanks iitimcoming

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