Device that transforms thermal energy to mechanical energy

the device that transfer thermal energy into to mechanical energy is heat engine.

hope it helps.

d

explanation:

i think the answer is d. but im not sure!

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.