Aball is thrown directly downward with an initial speed of 8.00 m/s, from a height of 30.0m. after what time interval does it strike the ground?

Plss anybody know how to do this? ? i need the answers from a through d

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?

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?