An airplane starts at rest and accelerates down the runway for 20 s. at the end of the runway, its velocity is 80 m/s north. what is its acceleration?

What is hidden during a lunar eclipse? isn't the moon hidden?

Mechanical energy is when the amount of kinetic and potential energies added together remains the same. conserved created lost

Why does the equilibrium position of the spring change when a mass is added to the spring? will the mass oscillate around the new equilibrium position of the spring or the previous position without a mass attached to the spring? if the equilibrium position of the spring changes by 20 cm (assuming no initial mass) when a mass is added to the spring with constant 4.9 kg/s^2, what is the mass of the object attached to the spring?