What happens when a substance undergoes a physical change?

a: some physical properties change, but the substance keeps its identity.
b: no physical properties change, and the substance keeps its identity.
c: some physical properties change, and the substance changes its identity.
d: no physical properties change, but the substance changes its identity.

What are the three ways that an object can accelerate

Acompound machine is also called a machine. a. force b. simple c. complex d. directional

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 =