Question

You throw a ball downward from a window at a speed of 2.0 m/s. How fast will it be moving when it hits the sidewalk 2.5 m below?

Answer 1

this will require the use of kinematic equations:
we have:
Vstarting = 2.0 m/s
HeightStarting = 2.5 m
and we need to find Vfinal

the kinematic equation of
V^2 = V^2 + 2ah can be used
velocity final ^2 = velocity starting ^2 + 2 * acceleration of gravity * change of height

there are two terms which we are given, velocity starting and change in height,
we are missing two terms: final velocity (which we are looking for) and acceleration of gravity.

acceleration of gravity is a number which is always the same, and can be found usually in the front or back cover of a physics book. we are using meters, so we will use 9.81 m/sec^2

so now we have 3 knowns, and one unknown.

all that is left is to plug the three known values into the kinematic equation I listed above, and use algebra to solve for the one unknown, which is final velocity.

Answer 2

i guess it would be better to use
s=ut+1/2at2

Answer 3

and find t

Answer 4

then use v=u+at

Answer 5

where s is the distance=2.5
u=initial speed=0
v=final speed which we have to find
a=acceleration which is due to gravity (take as positive)
t=time

Answer 6

if you want i will post the answer in 5 mins

Answer 7

@dan815