An aircraft has a net excess thrust of 14,000 lbs and weighs 36,000 lbs. if it starts from 30 kts, what is its velocity (in knots) after 15 seconds?

"(witch the answer is 141.218) you need this for the net part"

how many feet down the runway would the aircraft in problem 4 be at rotation if vr = 160 kts? (the aircraft is at 135 feet down the runway when it starts its takeoff and starts from 30kts)

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?