The
Pendulum Clock- Part 2
A 4th
Grade Science Project
Last
week we conducted experiments to determine what variables affect the =
period of the pendulum.
The period is =
the time
for one swing back and forth.
This
week we will put together our pendulum clocks.
Part A: Putting together your pendulum =
clock
You
should have the following parts:
1. =
Using the little screwdriver carefully screw =
the 18
small screws into the holes of the CD. Start
the screw on the side with the bobbin. This will form your =
pinwheel. Be careful not to press too hard =
to avoid
breaking the CD.
2. =
Tie the string around the bobbin which is on =
the back
of the CD.
3. =
Slide the pinwheel onto the shorter dowel =
near the
center of the base. The side =
with the
bobbin should face the base.
4. =
Attach a weight (washers) to the other end of =
the
string.
5. =
Slide the longer straw onto the longer dowel =
near the
top right corner of the base.
6. =
Slide the escapement onto this dowel making =
sure that
it can swing freely.
7. =
Slide the shorter straw onto the end. This =
straw will
keep the escapement from sliding off. It
should not be too tight.
8. =
Align the escapement and pinwheel as shown =
below. The long rod which forms the =
pendulum should
hang straight down just between the two arms of the =
escapement.
Part B: =
Starting the clock
1. =
Pull the escapement out a bit and turn the =
pinwheel
counterclockwise to wind up the string.
Be sure the string is wrapping around the bobbin, not the dowel =
behind
it.
2. =
When the string is all wound up, slide the =
escapement
back in. Put back the =
small straw that
holds it in place. Pull the =
escapement
gently to one side and let it go.
Part C: =
Calibrating your
clock
Do
this part with your partner.
1. =
Start your pendulum clock. =
2. =
Ask your partner to watch the clock on the =
wall and
say =93GO=94 when the second hand reaches a number and then say =
=93STOP=94 after 20
seconds. =
3. =
Count how many oscillations (or screws on the =
CD) go
by during those 20 seconds. =
Enter the
number in the first row of the table below. Repeat and enter the value =
in the
second row of the table.
|
|
# of Swings |
|
1 |
|
|
2 |
|
|
Average
|
|
4.
In the =
third row calculate
and report the average of the two numbers.
5.
Now help =
your
partner do the same thing for her/his pendulum =
clock.
Part D: The =
Challenge:
Testing your Pendulum Clock
The
teacher will give you an amount of time for you to =
test.
Write
it down here: _______________ seconds .
Use
your table in part C to calculate how many oscillations your clock will =
make
during the amount of time given by the teacher.
Write
it down here: _______________
oscillations. =
Start
your clock.
When
your teacher says =93GO=94 start counting oscillations of your =
clock. When you reach the number of =
oscillations
you wrote down say =93STOP.=94
The
teacher will tell you how many seconds went by.
Write
it down here _______________ =
seconds.
What
is the difference between the two times?
______________