How metronome work in theory physic? Can you help me figured it out, please?

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? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space. b. we'll know it immediately because it will be brighter than the full moon in the sky. c. we won't know about it until 600 years from now. d. none of the above.

Contrast the force of gravity between these pairs of objects: 1-kg mass and a 2-kg mass that are 1 m apart; a 1-kg mass and a 2-kg mass that are 2 m apart; and two 2=kg masses that are 1 m apart. i dont understand.