When a muscle contracts, it performs work. it does this by a) converting chemical energy to mechanical energy. b) converting mechanical energy into heat energy. c) converting mass into energy. d) creating energy.

A) converting chemical energy to mechanical energy.

When a muscle contracts, it performs mechanical work. The chemical energy generated in the muscle cell gets converted to mechanical energy. The oxidation of carbohydrates and fats helps in contraction of muscles. The metabolic process generates ATP molecules which is a storehouse of energy. during contraction. These molecules break to generate energy.

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.

answer and explanation;