Asap a roller coaster is 1/2 way down, what form of energy does this roller coaster have at this point? kinetic, potential, or both kinetic and potential energy?

Which is the best for showing percentages of different types of cars sold(gas hybrid , electric , other ) in the united states ?

John throws .4 kg ball with velocity of 18 m/s. hits .2 kg bottle and bottle flies 25 m/s. how fast is ball traveling after hitting the bottle?

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?