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

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.

d) physical means can be used to separate the components of air.