Answer:
Short circuit, closed circuit, open circuit
If the net force is zero, then there is no acceleration, which means no change in velocity. The velocity starts at zero, so it must remain at zero. Therefore, the object will not move.
Answer:
Answer C : person on an elevator going down
Explanation:
We look for a change in state of motion in order to have a net force different from zero in the system. The state of motion doesn't change in any of the examples a, b, or d. But there is a change in the state of motion in case c where initially the person and elevator where in static equilibrium, and later the elevator started going down and accelerating from zero speed to another non zero speed.
Because different materials have different molecular organizations.