Astudent throws a ball straight down off a very high building with a velocity magnitude of 3.0 m/s the ball accelerated in free fall for 2.0s what is the velocity at 2.0s

In a uniformly accelerated motion, the velocity follows the law:

where v(t) is the velocity at time t, v0 is the initial speed, a the acceleration.
In the free fall motion of the ball, the initial speed is , while the acceleration is the gravitational acceleration: . We take downward as positive direction, so all the signs are positive (because both initial velocity and acceleration point downwards). Replacing t=2.0 s, we find the magnitude of the velocity at t=2.0 s:

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

Kinetic energy = 1/2mv^2. since the mass is constant we can form a ratio of it's kinetic energy at 60 divided by that at 30 to see ke(60)/ke(30) = +(60^2)/30^2). this may be said to 300% increase.