A horizontal spring having constant k = 50.0 N/m is attached to a block having mass 0.50 kg. The mass is oscillating freely on a frictionless table with amplitude 15.0 cm. As the mass travels from equilibrium to half the position of maximum stretch, how much work is done by the spring on the mass?

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =