What is the energy, in keV, of 60 keV x-ray photons that are backscattered (i. e., scattered directly back toward the source) by the electrons in a target

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j ?

It is really hard for me right know

Abar magnet cut in half will form a total ofpoles.a)fourb)eightc)two