2. A force of 50 N is applied to the object for a distance of 2.0 m. Assume that object（the mass of the object is 3kg） was at rest at the beginning, what speed did it achieved because of the work done on it? (Hint:
Calculate the works performed by the force first.)

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 =