Answer:
Apply Newton's second law in the moving direction.
Explanation:

Friction force applies in the opposite direction of motion; as a restriction.
No,because a Kevin is 7.242971666663E+22 times Smaller than a Joule.
Any ride that oscillates back and forth or moves only in a complete circle utilizes periodic motion.
I<span>n </span>direct current<span> (</span>DC), the electric charge (current<span>) only flows in one direction. Electric charge in </span>alternating current<span> (</span>AC<span>), on the other hand, changes direction periodically. The voltage in </span>AC<span> circuits also periodically reverses because the </span>current<span> changes direction.</span>