Download - Physics

Form 3 Experiments
Theme 1: On The Move
Aim: To investigate Conservation of Energy
OBJECTIVE: To investigate the Kinetic and Potential Energy changes
for a falling object.
Focus Questions
1.
What do you understand by Potential Energy and Kinetic
Energy? What type of energy has a stationary object that is
at a certain height and can fall down? What type of energy
has an object that is moving?
2.
Is Potential energy related to Kinetic energy? If yes how?
3.
How does the GPE change as the height from which the ball is
dropped changes? Where is the PE greatest? Smallest? Where
is the KE greatest? Smallest? How do you account for the
change in GPE?
4.
What are some of the factors that affect the amount of PE in
a system?
5.
How do outside factors, such as gravity, friction, and air
resistance, affect the amount of PE that is transferred to KE in
a system?
Safety Notes:
In this experiment, we will use data loggers. Handle with care. Pay
attention to the measurements taken. Make sure stand and clamp are
stable so they do not topple over.
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Date: ____________
Theme 1: On The Move
Aim: To investigate Conservation of Energy
Apparatus: Nova 5000 data logger, velocity sensors, plasticene,
mass balance, ruler, stand and clamp, tennis ball.
Sources of error and precautions 1.
2.
Method
a. Press the plasticene into a round ball and determine its mass in
grams using a mass balance. Convert to kilograms and record the
data.
b. Adjust the light gate on a clamp and stand. Fix a metre ruler
vertically on another clamp and stand.
c. Switch Nova 5000 on. Ensure that the AC/DC adapter is connected.
d. Launch MultiLab . Attach the light gate to Input 1 (I/O-1) of the
Nova5000. Click Logger on the menu bar, and then click Timing Wizard.
Choose velocity and click timing wizard – Method. Choose at one gate
and enter width in cm. Press OK.
e. One student holds the plasticene 60 cm from bench directly
above the light gate. The light gate is placed 50 cm above bench.
(Distance fallen by plasticene = 10 cm). The ball is released and the
velocity recorded from the data logger.
f. Repeat this procedure four times for the same height.
g. The light gate is now placed 40 cm above bench. (Distance fallen
by plasticene = 20 cm). The velocity is again recorded.
h. This is repeated for all the heights seen in table 1.
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i. Calculate the average velocity and calculate the Kinetic energy of
the ball.
j. Work out the potential energy at different heights and fill in
table 2.
k. Predict the results obtained if a tennis ball is dropped instead of
the plasticene from the same height. Will the values be the same,
bigger or smaller? Why? Repeat this activity, dropping the ball
and plasticene from a known height. Is the velocity the same or
different? Why?
Mass of plasticene in grams = ___________________
Mass of plasticene in Kilograms = ________________
Potential energy at 0.60 m = mgh = ________________ J
Table 1
Height
fallen - m
0
Velocity
1 – m/s
Velocity
2 – m/s
Velocity
3 – m/s
Velocity
4 – m/s
Average
velocity
KE - J
½ m v2
0.10
0.20
0.30
0.40
0.50
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Table 2
Height
fallen - m
Height above
bench - m
0
Potential
Energy
mgh - J
Kinetic
Energy
-J
Potential +
Kinetic
Energy - J
0.6
0.10
0.5
0.20
0.4
0.30
0.3
0.40
0.2
0.50
0.1
0.60
0.0
Draw a graph of Energy on the x- axis against height above bench
y – axis. From graph determine the maximum kinetic energy.
Conclusion /Evaluation:
1. Make a diagram of your apparatus setup.
2. What happens to the Potential energy as the height from which the
ball is dropped changes? Where is the PE greatest? Smallest?
3. What happens to the Kinetic energy as the height fallen by ball
increases? Where is the KE greatest? Smallest?
4. What are some of the factors that affect the amount of PE in a
system?
5. How do outside factors, such as gravity, friction, and air
resistance, affect the amount of PE that is transferred to KE in a
system?
6. Is the total energy conserved at all times? If yes, how well is it
conserved? At which height is PE = KE.
7. Did the tennis ball had the same values as plasticene when
dropped from the same height. Discuss your observation.
8. Discuss the major sources of error that would account for your
discrepancies.
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