The change in internal energy during one complete cycle of a heat engine a. equals the net heat flow into the engine. b. equals zero. c. equals the heat energy exhausted from the engine. d. equals the heat energy entering the engine.

B. equals zero

Explanation:

Given data

one complete cycle = heat flow

solution

we have given that when heat engine complete 1 cycle change in energy = net heat flow

that is always equal to zero

from first law of thermodynamics that

ΔU = Q + W

we know ΔU is the change internal energy in system and Q is net heat transfer in system and W is  net work done in system

therefore change of internal energy during one cycle

ΔU = Ufinal -  Uinitial

ΔU  = Uinitial  -  Uinitial  = 0

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.