A block of mass M slides along a horizontal table with speed `v_(0)`. At `x=0`, it hits a spring with spring constant k and begins to experience a friction force. The coefficient of friction is variable and is given by `mu=bx`, where b is a positive constant. Find the loss in mechanical energy when the block has first come momentarily to rest.
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A. `(gbMv_(0)^(2))/(2k)`
B. `(Mgbv_(0)^(2))/(2(k+gb))`
C. `(gbMv_(0)^(2))/(k)`
D. `(M^(2)gbv_(0)^(2))/(2(k+Mgb))`
