The velocity is zero but the speed is a nonzero quantity?

The least penetrating form of radiation is

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?

What kind of air would be characteristic of a continental polar air mass? o a cold, dryob. warm, humido c. warm, dryo d. cold, wet