Aball is kicked from the top of a building with a velocity of 50 m/s and lands 165 m away from the base of the building.
a) how much time does it take for the ball to hit the ground?

3.1 s

Explanation:

we can assume that this motion has a horizontal projectile motion.

projectile motion happens when  an object is subjected to only gravity. Gravity acts to influence the vertical motion of the projectile, it makes a  vertical acceleration.  

The horizontal motion of the projectile is the result of the constant velocity of the object.We assume no acceleration in the horizontal direction.  

applying motion equations

where

s - distance

u - initial velocity

a-acceleration

t - time

s = ut + (1/2)at²

→ 165 = 50t + 0 (as no acceleration is in horizontal direction)

t = 3.1 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 -