[click here for printable version]
Worksheet4: Free Fall
Galileo, with his numerous experiments was able to
find out 2 very important things:
-
All objects, independent of their size, shape or mass
fall towards the earth in the same way. This means that a feather and an
elephant will take the same time to fall from the same cliff.
-
The so-called "free fall movement " is an accelerated
movement, with constant acceleration. It is similar to the movement of
a car accelerating on a freeway, with the difference that it is an up-down
acceleration.
Let's explore a bit what all this means:
-
Go to the web site: http://www.explorescience.com/freefall.htm
Here we can experiment with different sizes and masses
of a ball in different types of atmosphere. All of this is done by "computer
simulation." Simulations are just like games, where the laws of physics
tell us what is going on.
In this page:
-
Mass (kg): Mass of the ball being released by the hand
above. We can adjust the mass of the ball between 0.01kg (10 grams) and
0.5kg (500 grams)
-
Radius (m): radius (size of the ball). One diameter
is 2 times the radius of a ball. We can have a ball as small as 0.01m radius
(10 cm radius = 20 cm diameter) and a ball as large as 1m radius (2 m diameter.
This is a VERY BIG ball). Unfortunately the simulation does not change
the sizes in the drawing, but we can use our imagination to check it out.
-
Height (m): Height from which we drop the ball. It goes
from 1m to 100m.
-
Wind speed (m/s): This is a tricky one. We can make
downward-going wind and upward-going wind in this gameÖ The upward-going
strongest wind is ó1m/s and the downward -going strongest wind is
+1m/s.
-
Air density (kg/m3): How "heavy" is the air
or atmosphere we are playing with here? 1kg/m3 air density means
that 1 cubic meter of air weighs 1 kg. 1kg/m3 is the same as
0.001g/cm3. To give you idea, waterís density is 1g/cm3
but we will not be using this buttonÖ.
-
Delta t in seconds: is the size of the time intervals
we look at our falling ball. We will not be dealing with it eitherÖ.
Other controls are bouncing, and how to plot the graph.
QUESTION 1: The table below describes the
settings for this question.
| Setting |
Mass(kg) |
Radius(m) |
Height(m) |
Wind(m/s) |
Air Dens. (kg/m3): |
Delta T(s) |
| 1 |
0.01 |
0.01 |
10 |
0 |
0 |
0.03 |
| 2 |
0.5 |
0.01 |
10 |
0 |
0 |
0.03 |
| 3 |
0.01 |
1 |
10 |
0 |
0 |
0.03 |
| 4 |
0.5 |
1 |
10 |
0 |
0 |
0.03 |
What is the time it takes for the ball to fall for
each one of the settings above? Record your answer below. (The time is
shown next to the graph on the left.)
| Setting |
Time it takes (s) |
| 1 |
|
| 2 |
|
| 3 |
|
| 4 |
|
What is your conclusion?
QUESTION 2: The table below describes the
settings for this question.
| Setting |
Mass(kg) |
Radius(m) |
Height(m) |
Wind(m/s) |
Air Dens. (kg/m3): |
Delta T(s) |
| 1 |
5 |
0.01 |
10 |
0 |
0 |
0.03 |
| 2 |
5 |
0.01 |
10 |
0 |
1.5 |
0.03 |
| 3 |
5 |
0.01 |
10 |
0 |
3.5 |
0.03 |
| 4 |
5 |
0.01 |
10 |
0 |
5 |
0.03 |
What is the time it takes for the ball to fall for
each one of the settings above? Record your answer below. (The time is
shown next to the graph on the left.)
| Setting |
Time it takes (s) |
| 1 |
|
| 2 |
|
| 3 |
|
| 4 |
|
What is your conclusion?
QUESTION 3: The table below describes the
settings for this question.
| Setting |
Mass(kg) |
Radius(m) |
Height(m) |
Wind(m/s) |
Air Dens. (kg/m3): |
Delta T(s) |
| 1 |
5 |
0.30 |
10 |
0 |
0 |
0.03 |
| 2 |
5 |
0.30 |
10 |
0 |
1.5 |
0.03 |
| 3 |
5 |
0.30 |
10 |
0 |
3.5 |
0.03 |
| 4 |
5 |
0.30 |
10 |
0 |
5 |
0.03 |
What is the time it takes for the ball to fall for
each one of the settings above? Record your answer below. (The time is
shown next to the graph on the left.)
| Setting |
Time it takes (s) |
| 1 |
|
| 2 |
|
| 3 |
|
| 4 |
|
What is your conclusion?
QUESTION 4: The table below describes the
settings for this question.
| Setting |
Mass(kg) |
Radius(m) |
Height(m) |
Wind(m/s) |
Air Dens. (kg/m3): |
Delta T(s) |
| 1 |
5 |
0.01 |
10 |
0 |
0.3 |
0.03 |
| 2 |
5 |
0.4 |
10 |
0 |
0.3 |
0.03 |
| 3 |
5 |
0.7 |
10 |
0 |
0.3 |
0.03 |
| 4 |
5 |
1. |
10 |
0 |
0.3 |
0.03 |
What is the time it takes for the ball to fall for
each one of the settings above? Record your answer below. (The time is
shown next to the graph on the left.)
| Setting |
Time it takes (s) |
| 1 |
|
| 2 |
|
| 3 |
|
| 4 |
|
What is your conclusion?
|
