An object of mass m is held at rest a distance Re above the earth’s north pole, where Re is the radius of the earth and g is the accelera- tion due to gravity on the surface. If the object is allowed to fall, with what speed does it hit the surface? Ignore the mo- tion of the earth around the sun, and friction with the earth’s atmosphere.

Why is there friction between objects

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

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".