Pick 1 or 2 When you stand on a cliff holding a ball, the ball has potential energy. When you drop the ball, it starts moving and gains kinetic energy. For now, these simple definitions will do: 1. Potential energy ⇔ energy of being up high
2. Kinetic energy ⇔ energy of moving

Critical mass is the of material required to produce a chain reaction. a.) minimum amount b.) atomic mass c.) precise amount d.) maximum amount

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)

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 =