19discussed several times earlier !
A block of mass m is lowered from natural length position of spring slowly by an external agent to equillibrium position .The extension present in the mass less spring was asked from 2 students
Student A : 1/2 kx2 = mgx
=> x = 2mg/k
Student B : mg = kx
=> x = mg/k
(A) Only A is correct
(B) Only B is correct
(C) Both correct
(D) Both wrong
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13 Answers
1the answer is (B) becausenet force in d situation is 0 but non0 in(A)
6mg is an external force??m getting confused wid dat....
6oh i got it.... g is an external force....bt wat is wrong wid the 1st option??
11 / 2 kx^2 ≠mgx
we have to consider the total displacement of com , { to conserve energy ,} which is x / 2 , not x .
so 1 / 2 k x^2 = m g x / 2
or x = mg / k
1The word "slowly" means that at each position an equilibrium is set up. thus in such a quasi-static process the 2nd option holds true.
1Yes.Soumya, couldnt quite understand ur reasoning about the centre of mass.
6cud anyone pls tell me wat the hell is wrong in the 1st option.....???
1Yes kalyan...u conserve energy whn the entire system is in equilibrium not STATIC. if the word "slowly" hadn't been der...the ist option would have held true.