Please explain what these are and give simple examples if you can: -centripetal force

-centrifugal force

-direction of the velocity

Astone dropped into a well is heard to strike the water after 8seconds. find the depth of the well if the velocity of sound is 350m/s

Aman throws a football straight into the air. as it rises, it slows down. which type of energy is the football gaining?

Engineers find a new metal that is stronger than steel but much lighter. this material is also significantly cheaper than what is currently used for most aircraft, available in large quantities, and easy to manufacture. the engineers are excited because this new material will lower the costs of buying and operating airplanes for companies. what is probably the best step for the engineers to make next?