newton law

in the arrangement shown, the ends P & Q of an unstrecthable string move downwards with uniform speed U. pulleys A & B are fixed.
find the speed with which mass M moves upwards ?

8 Answers

3
msp ·

aman is it 2ucosθ

1
big looser ......... ·

no its u/cosθ

1
big looser ......... ·

arey koi to reply karo

1357
Manish Shankar ·

take the net workdone by tension as zero...

2UT+Vcosθ(2T)=0

Thus,

v=u/cosθ

1
Philip Calvert ·

plz explain bhaiyya how net workdone by tension = zero
the mass is rising isn't it [7]

62
Lokesh Verma ·

Take the system as all the pulley and the end of the string too...

tension is an internal force.

Work done by internal forces is zero...

Take work done as

F.s on each of the points on the string...

There is zero net force at a points within the string... because the string is massless.

1
Philip Calvert ·

thanx [4] got it
it came in jee once i suppose

1
big looser ......... ·

thanks everyone .............................

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