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gourish
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Homework Statement
There are two cubes of mass m. They are initially tied by a string tightly. They are kept from joining into each other because of a spring (which in this tied up state has a compression of ε) of coefficient of stiffness k. Find the minimum value of the quantity εk/mg so that when the string is cut and the spring is let loose to act, the lower cube jumps off the ground
Homework Equations
consider the natural length as "l" of the spring and the center of mass of lower cube as the reference line
total mechanical energy (initial)=1/2 k ε^2+mg (l-ε)
total mechanical energy (after)=1/2kx^2+mg(l-x)
The Attempt at a Solution
i found that k(e+x)/mg=2 but i did not get to the quantity to become εk/mg and did not understand how to relate the equations to the condition "the lower cube jumps off the ground" can anybody please help me