4. an object (object a) with a mass of 500 kg is traveling in a straight line from west to east at a constant velocity of 34 m/s. object a encounters a headwind blowing with a force of 25 n for six minutes and then proceeds to collide with a stationary object (object b) with a mass of 300 kg, thereby reducing the velocity of object a to 4 m/s. what is the final velocity of object b?

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 =