Answer:
Superconducting materials can transport electrons with no resistance, and hence release no heat, sound, or other energy forms. Superconductivity occurs at a specific material's critical temperature (Tc). As temperature decreases, a superconducting material's resistance gradually decreases until it reaches critical temperature. At this point resistance drops off, often to zero, as shown in the graph at right.
Explanation:
Yes. It means that the acceleration increases at a constant rate, for example 3 mph every second.
Answer:
D. gravity
Explanation:
Gravity keeps the atmosphere from escaping into space.
Answer:
a)
, b) 
Explanation:
a) The equation for vertical velocity is obtained by deriving the function with respect to time:

The velocities at given instants are, respectivelly:

