A wedge of mass M fitted with a spring of stiffness 'k' is kept on a smooth horizontal surface. A rod of mass m is kept on the wedge as shown in the figure. System is in equilibrium. Assuming that all surfaces are smooth, the potential energy stored in the spring is:

Question

G1 Physics · Accepted Answer

For the vertical rod to remain in equilibrium, the contact force from the wedge gives horizontal component mg tanθ on the wedge. Hence spring force kx=mg tanθ. Therefore spring energy ½kx²=m²g²tan²θ/(2k). Hence C.