Plis help me

An object is dropped from a tower, 400 ft above the ground. the object's height above ground t seconds after the fall is s(t)equals400 minus 16 t squared. determine the velocity and acceleration of the object the moment it reaches the ground. the velocity of the object the moment it reaches the ground is nothing ft/s.

Which units can be used to measure length or distance? check all that apply. gram meter kilometer liter inch

Carbon-14 is a radioactive element that undergoes beta decay. which force is responsible for allowing carbon-14 to become stable? electromagnetic gravitational weak nuclear strong nuclear