PLEASE HELP with these questions ASAP. (show work) Thank you so much! I will mark brainliest also the topic is special relativity.

What is the function of the commutator in a dc motor? a. to spin the magnet b. to change direct current into alternating current c. to change alternating current into direct current d. to spin the wire coil

How would doubling the made of an object change the objects potential energy

If it takes a planet 2.8 x 10^8 s to orbit a star with a mass of 6.2 x 10^30 kg what is the average distance between the planet and the star