PLEASE HELP What causes an electric charge?

A. The movement of electrons due to a difference in electric potential energy

B. The movement of protons due to a difference in electric potential energy

C. The movement of neutrons due to a waterfall

D. The movement of electrons due to kinetic energy

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

Air initially at 0.75 bar, 1000 k, and occupying a volume of 0.12 m^3 undergoes two processes. process 1-2: the air is compressed isothermally until the volume is halved. process 2-3: the air undergoes a constant pressure process until the volume is halved again. assume ideal gas behavior. a) determine the mass of the air, in kg. b) the work and the heat transfer for each of the two processes, in kj. (100 kj = 1 bar . m^3)

Which features on mars point to the possibility of liquid water on the planet? impact craters with sharp rims volcanic cones with craters gullies and stream-like channels mountain ranges with faults