Part 1 of 2 Bill kicks a rock off the top of his apartment
building. It strikes a window across the street
18 m away.
The acceleration of gravity is 9.8 m/s?.
If the window is 19 m below the position
where Bill contacted the rock, how long was
it in the air?
Answer in units of s.
part 2 of 2
How fast was it moving when it left Bill's
foot?
Answer in units of m/s.

I got you.. i'm in middle school and had that same question.

Explanation:

Refer to the diagram shown below.

The vertical distance traveled is

s = 25 m

The initial vertical launch velocity is zero.

Therefore

s = (1/2)*g*t²

where g = 9.8 m/s²

t = the time of flight, s

That is,

0.5*9.8*t² = 25

t² = 25/4.9 = 5.102

t = 2.26 s

2.26 s

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

continuous conducting path for current, power supply