An ideal heat engine absorbs heat at 100°c and exhausts heat at 0°c. what is its percent efficiency?

26.8 %

Explanation:

TH = 100°C = 100 + 273 = 373 K

Tc = 0°C = 273 K

The efficiency of the heat engine is given by

η = 0.268

η = 26.8 %

Thus, the efficiency of the heat engine is 26.8 %.

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.