Please help me with physics, “resistance”

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

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

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?