Question

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.

Answer 1

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

Step-by-step 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

Answer: 2.26 s