Question

Which of these is true about mechanical energy?

Answer 1

Mechanical energy is always conserved.

The mechanical energy of an object increases in free fall.

Mechanical energy sometimes changes into thermal energy.

Some of the mechanical energy in a system can simply disappear during an energy transformation.

Answer 2

According to Newton's Laws, energy is neither created nor destroyed. Usually if something appears to be losing energy, energy is being gained by another system. The third answer appears to be the correct response. If a person is running, the mechanical energy that is produced from their limbs will produce heat. This is why we sweat when we exercise to allow us to keep our bodies cool. Therefore, mechanical energy can me converted into various forms of energy. In free fall, the only factor that is acting on an object is the force of gravity, all other factors, such as air resistance are not taken into account. The kinetic energy will increase as an object is in free fall, but not the mechanical energy. Therefore, the third answer would be the correct answer. Other examples of this would be lighting a match. The mechanical energy becomes converted into heat energy. Hope this helps :)

Answer 3

thank you!