A 1.5 kg block sliding on a rough horizontal surface (coefficient of friction of 0.34) is attached to one end of a horizontal spring (k = 200 N/m) which has its other end fixed. If this system is displaced 0.20 m horizontally from the equilibrium position and released from rest, how fast is the block moving when it passes the equilibrium position for the first time?

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?