General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 1 / 20
[For International Campus Lab ONLY]
Circular Motion and Centripetal Force
Measure the centripetal force with the radius, mass, and speed of a particle in uniform circular motion.
When a particle moves in a circle with constant speed, the
motion is called uniform circular motion. There is no com-
ponent of acceleration parallel to the path. The acceleration
vector is perpendicular to the path and hence directed inward
toward the center of the circular path. This causes the direc-
tion of the velocity to change without changing the speed.
Fig. 1(a) shows a particle moving with constant speed in a
circular path of radius with center at . The particle
moves from to in a time Δ . The vector change in
velocity during this time is shown in Fig. 1(b). The an-
gles Δ in Fig. 1(a) and 1(b) are the same because is
perpendicular to the line and is perpendicular to the
line , so
| | Δ
or| | Δ (1)
The magnitude of the average acceleration during Δ is
| |
ΔΔΔ
(2)
The magnitude of the instantaneous acceleration at
point is the limit of this expression as we take point
closer and closer to point
lim→
ΔΔ
lim→
ΔΔ
(3)
Fig. 1 Finding the velocity change , average accelerat-
ing , and instantaneous accelerating for a particle moving in a circle with constant speed
Objective
Theory
----------------------------- Reference --------------------------
Young & Freedman, University Physics (14th ed.), Pearson, 2016
3.4 Motion in a Circle (p.106~109)
4.3 Newton’s Second Law (p.132~136)
5.4 Dynamics of Circular Motion (p.174~175)
-----------------------------------------------------------------------------
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 2 / 20
If the time interval Δ is short, Δ is the distance the parti-
cle moves along its curved path. So the limit of Δ Δ⁄ is the
speed at point . Also, can be any point on the path,
so we can drop the subscript and let represent the speed
at any point. Then
(4)
In uniform circular motion, the direction of the instantaneous
acceleration is perpendicular to and inward along the radi-
us, i.e. toward the center of the circle as in Fig. 1(c). Because
of this reason, the acceleration in uniform circular motion is
sometimes called centripetal acceleration. The word “cen-
tripetal” is derived from two Greek words meaning “ seeking
the center.” Fig. 2 shows the direction of the velocity and ac-
celeration vector at several points for a particle moving uni-
form circular motion.
We can also express the magnitude of the acceleration in
uniform circular motion in terms of the period (the time for
one revolution) of the motion. In a time the particle travels
a distance equal to the circumference 2π of the circle, so
its speed is
2
(5)
Substituting Eq. (5) into Eq. (4) yields
4
(6)
Fig. 2 Acceleration and velocity for a particle at uniform
circular motion
Uniform circular motion, like all other motion of a particle, is
governed by Newton’s second law, ∑ . To make the
particle accelerate toward the center of the circle, the net
force ∑ on the particle must always be directed toward the
center as in Fig. 3. The magnitude of the acceleration is con-
stant, so the magnitude of the net force must also con-
stant. If the inward net force stops acting, the particle flies off
in a straight line tangent to the circle, as in Fig. 4.
The magnitude of the net force on a particle with mass
in uniform circular motion is then
(7)
Fig. 3 Net force, acceleration and velocity in uniform circular motion
Fig. 4 What happens if the inward radial force suddenly ceases to act on a body in circular motion?
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 3 / 20
1. List
Item(s) Qty. Description
PC / Software
Data Analysis: Capstone
1 Records, displays and analyzes the data measured by
various sensors.
Interface
1
Data acquisition interface designed for use with various
sensors, including power supplies which provide up to
15 watts of power.
Force Sensor
1
Measures the magnitude of force.
Range: 50N~50N
Resolution: 0.03N
Photogate
(Cable included)
1 Measures high-speed or short-duration events.
Circular Motion Apparatus 1 Allows objects to undergo uniform circular motion using
electric motor.
Swivel
1 Allows connected objects to rotate.
Wire
1 Connects the Mass to the Force Sensor
Mass Set 1 set
Includes 8 masses
- Free mass: Hook embedded
- Fixed mass: Perforated
- Plastic, Aluminum, Al. with Brass, and Stainless Steel
Fixed Mass Holder
(Nut included)
1 Secures a fixed mass.
Equipment
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 4 / 20
Item(s) Qty. Description
Bubble Level
1 Checks the level of a surface.
Patch Cords
(with banana plugs)
2 Carry electric current.
A-shaped Base
Multi-clamp
Support Rod 600mm
Support Rod 300mm
1
1
1
1
Provide stable support for experiment set-ups.
Electronic Balance
Measure mass.
2. Details
(1) Photogate
The Photogate sensor is an optical timing device used for
very precise measurements of high-speed or short-duration
events. It consists of a light source (infrared LED) and a light
detector (photodiode). When an object moves through and
blocks the infrared beam between the source and the detec-
tor, a signal is produced which can be detected by the inter-
face.
When the infrared beam is blocked, the output signal of the
photogate becomes ‘0’ and the LED lamp on the photogate
goes on. When the beam is not blocked, the output signal
becomes ‘1’ and the LED goes off. This transition of signal
can be used to calculate quantities such as the period of a
pendulum, the velocity of an object, etc.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 5 / 20
(2) Force Sensor
The Force Sensor measures both pulling and pushing forc-
es in the range of 50N to 50N.
The sensor uses a strain gauge attached to an aluminum
beam. The gauge consists of an insulating flexible backing
which supports a metallic foil pattern. As the aluminum beam
is deformed, the foil is deformed, causing its electrical re-
sistance to change. The gauge is wired to form a full-bridge
circuit that is driven by a constant voltage source. The volt-
age across the bridge circuit is proportional to the applied
force.
(3) Mass Set
Free Mass Fixed Mass
Use Measuring Force Balancing
Shape
with Hook
with Center Hole
How
to useHook it to the wire.
Secure it to the rotating
arm using a mass holder.
MassMeasure the mass using
an electronic balance.
Do not have to measure
the mass.
Material Color Mass range g
Plastic White 11.50~12.50
Aluminum Light Gray 23.50~24.50
Al + Brass Gray / Yellow 43.00~44.00
Stainless Steel Dark Gray 66.50~67.50
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 6 / 20
Setup 1. Equipment Setup
Setup
CAUTION
To avoid possible injury from the rotating arm hitting the
body, keep at least 1m distance from the rotating arm
when running the motor.
To avoid damaging the apparatus, keep all cords away
from the rotating arm.
To avoid damaging any other equipment or facilities near
the apparatus, especially your LCD monitor, keep the
apparatus away from them.
CAUTION
Do not tighten the swivel too hard. It could cause the
sensor to fail.
NOTE
① Thread the wire from the swivel hook through the pul-
ley as shown below.
② Hook the free mass to the end of the wire.
③ Hold the fixed mass firmly using the mass holder.
NOTE
To adjust the rotational radius of a free mass, lower or
raise the height of the upper (horizontal) support rod.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 7 / 20
Setup 2. Software Setup
(1) Run Capstone software.
(2) Add a Photogate.
Click the input port which you plugged the Photogate into
and select [Photogate] from the list.
(3) Create and configure a timer.
To measure the period of the circular motion, click [Timer
Setup] in the [Tools] palette and follow the steps below.
① Create a timer.
Choose [Build your own timer].
② Select the timing device for the timer.
Check [Photogate, Ch1] and then click [Next].
③ Arrange the sequence of timing events.
When the rod of the fixed mass holder passes the Photo-
gate, the Photogate beam is blocked and a “Blocked” signal
is generated. The time interval between the signals equals
the period of the motion, the time for one revolution. (You
will use this measurement to calculate the speed of the mass
in step (5).)
Click [▼] and then select [Blocked].
Click [▼] again and select [Blocked] one more time. Now
you have two [Blocked] events as below. Click [Next] for the
next step.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 8 / 20
④ Specify the timer’s name.
Enter the name of the timer (“period” is recommended) and
click [Finish].
(5) Configure calculator.
In a period , the mass travels a distance equal to the cir-
cumference 2π of the circle, so its speed is
2
(5)
The period will be measured through the process defined
in step (4). Now you define and using [Calculator].
Define the speed of the mass. Enter the equation of in
the first row of the [Calculator].
To define the equation 2 / , type “v=2*pi*R/” and “[“.
Make sure that you enter a left-bracket “[“ instead of “T” be-
cause you will insert “measured” data for . (Unlike numerals
or math functions, “measured” data are given in brackets
“[“ and “]”.)
When you type “[“, a pop-up list appears as below.
Select [period(s)], which you named in step (4). When you
select it, the equation is completed as shown below.
When you press the enter key, two cells are automatically
typed. One is for the unit of the parameter of the first equation,
and the other is for the variable R which you do not define yet.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 9 / 20
Enter the unit of the speed .
Enter the value and unit of R. You have to enter a correct
value for R whenever you vary the radius of the circular
path of the mass.
(6) Configure the Force Sensor.
The interface automatically recognizes the Force Sensor.
If the sensor is not in the panel, click the input port which
you plugged the sensor into. A drop down menu of sensors
will appear. Select [Force Sensor, High Resolution] from the
list and the sensor’s icon will be added to the panel.
Click the Force Sensor icon in the [Hardware Setup] panel
and then click the properties button (☼) in the lower right cor-
ner.
In the [Properties] window, check [Change Sign].
The sign of the outputs of the Force sensor is initially posi-
tive for the pressing force and negative for the pulling force.
In this experiment, you will measure the pulling force so you
have to change the sign of the outputs.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 10 / 20
(7) Configure the signal generator.
Do not add any sensor for [OUTPUTS 1].
Click [Signal Generator] in the [Tools] palette, and select
[850 Output 1].
Change the [Waveform] of the generator to [DC].
Set the [DC Voltage] to 4V.
Click [Auto] button to automatically activate the generator.
NOTE
Output options of [Signal Generator]:
[On] : The signal generator always output the signal.
[Off] : The signal generator is not activated.
[Auto] : The signal generator automatically outputs the
signal when you start recording, and automatically stops
when you stop recording.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 11 / 20
(8) Create displays.
You need 4 displays.
Data Table - -
Graph 1 -
Graph 2 -
Digital Meter
Click and drag [Table], [Graph], or [Digits] icon from the
[Displays] palette into the workbook page.
① Configure [Table] display.
[Table] display initially has two columns. To insert one more
column, click [Insert empty column] icon.
Click <Select Measurement> of each column and select
Time(s), Force(N), and v(m/s). Time(s) is a fundamental
measurement which shows the elapsed time from when the
measurement starts.
You can see the table as below.
② Configure [Graph] displays.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 12 / 20
Click <Select Measurement> to define the variables of each
axis.
Make a - graph. Select Time(s) for the -axis and
Force(N) for the -axis.
In the same way, make a - graph. Select v(m/s) for the
-axis and Force(N) for the -axis
③ Configure [Digits] display.
Drag [Digits] from the [Displays] palette into the workbook
page, and select v(m/s).
Move and resize the individual displays for easy view.
(9) Adjust the sample rate of the measurement.
Select [10.00Hz ] (collecting data every 0.1 second) for the
sensor in the [Controls] palette.
(10) Start/Stop recording data.
Click the [Record] button at the left end of the [Controls] pal-
ette to begin recording data. It will toggle to [Stop]. Click [Stop]
to stop data collection.
You can delete any data run using [Delete Last Run] or
drop-down menu in the [Controls] palette.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 13 / 20
Experiment 1.
In this experiment, you will vary the speed by changing
the voltage to the electric motor as the centripetal force is
continuously measured by the Force Sensor. The radius
and mass are held contant as the speed is increased.
(1) Follow the equipment setup instruction.
[Setup 1. Equipment Setup] on page 6
(2) Follow the software setup instruction.
[Setup 2. Software Setup] on pages 7-12
(3) Set the radius and the mass.
① Mount a set of masses (heavier set recommended).
② Adjust the radius (9cm is recommended) of the free mass.
To vary the radius, adjust the height of the Force Sensor,
keeping the wire tight.
③ Place the fixed mass at the same radius as the free mass
to ensure balancing the arm as it rotates.
④ Be sure to enter the correct value for in the calculator.
If the radius of the circular path of the mass is 9cm, enter
0.09 m .
Procedure
NOTE
Mass set Information
Free Masses Fixed Masses
Use Measuring Force Balancing
Shape
with Hook
with Center Hole
How
to use Hook it to the wire.
Secure it to the rotating
arm using a mass holder.
Mass Measure the mass using
an electronic balance.
Do not have to measure
the mass.
Material Color Mass range g
Plastic White 11.50~12.50
Aluminum Light Gray 23.50~24.50
Al + Brass Gray / Yellow 43.00~44.00
Stainless Steel Dark Gray 66.50~67.50
Measure the mass of free masses using the electronic
balance on the lecture table at the front of the lab.
Free Masses Mass g
Plastic
Aluminum
Aluminum + Brass
Stainless Steel
NOTE
Prior to recording each data run, press the [Zero] button
on the Force Sensor to zero the sensor.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 14 / 20
(4) Set the speed.
Speed is varied by changing the voltage supplied to the
electric motor. This will be displayed on [Digits] display. Apply
4, 5, 6, 7, and 8VDC to the motor.
Set [DC Voltage] of [Signal Generator] at 4V.
(5) Measure the force.
Click the [Record] button at the left end of the [Controls]
palette to begin recording data.
As the rotating arm rotates, the displays show the speed of
the mass and the force acting on the sensor. Wait a second
for stable rotation.
(6) Repeat measurement.
Repeat measurement for 4, 5, 6, 7, and 8VDC.
(7) Stop data collection.
Click the [Stop] button to stop data collection.
(8) Analyze the data.
Click [Show coordinates…] to read off data points.
(9) Repeat experiments.
Repeat measurement more than 3 times for each voltage
and calculate the average value to reduce the possibility of
experimental error.
NOTE
You can use [Pin] tool for easy view of the displays
.
NOTE
Collected data are stored in memory and appear in all
displays. The data runs are listed in the legend for each
display. (You can delete any run by clicking [Delete Last
Run] or drop-down menu in the [Controls] panel.)
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 15 / 20
(10) Record your results.
Mass Radius Speed Force
(Theo.)
Force
(Result)
kg m m/s kg ⋅ m⁄ N
(11) Plot - graph.
Plot - graph and verify the centripetal force is propor-
tional to the square of the speed. Use the method of least
squares if required. (Refer to the appendix of [Free Fall] ex-
perimental manual.)
CAUTION
It is strongly recommended that you save the data file
with a different file name if you need to change the value
in the calculator. Changing makes all pre-measured
speed recalculated with the new value .
NOTE
If - graph vibrates as below,
① Make sure all the rotating parts are aligned.
② It could occur due to mechanical problems of the
swivel ball bearing. In this case, search the data for the
time interval of interest and calculate the average value of
the force to find the experimental value.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 16 / 20
Experiment 2.
In this experiment, the radius and the speed are held
contant as the mass is varied. By replacing the mass set,
the mass of the system becomes increased.
(1) Follow the equipment setup instruction.
[Setup 1. Equipment Setup] on page 6
(2) Follow the software setup instruction.
[Setup 2. Software Setup] on pages 7-12
(3) Set the radius and the speed.
① Set [DC Voltage] of [Signal Generator] at 7V.
② Adjust the radius (9cm is recommended) of the free mass.
③ Place the fixed mass at the same radius as the free mass.
④ Enter 0.09 m for the radius in the calculator.
(4) Set the mass.
Use the lightest mass set.
(5) Measure the centripetal force.
Click the [Record] button at the left end of the [Controls] pal-
ette to begin recording data.
As the rotating arm rotates, the displays show the speed of
the mass and the force acting on the sensor. Wait a second
for stable rotation.
Record the speed. This value will be used to fine-tune the
voltage in the step (7).
Repeat measurement more than 3 times for each mass and
calculate the average value to reduce the possibility of exper-
imental error.
(6) Stop data collection.
Click the [Stop] button to stop data collection.
(7) Replace the mass set.
For all mass sets, repeat the steps (5) and (6).
Make sure the speed is equal to that of step (5). The speed
could be slightly different for each mass set even if the volt-
age remains constant, i.e. you need to fine-tune the voltage
for the each mass set.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 17 / 20
(8) Analyze the result.
Click the icon below to select the data run of interest.
Click [Show coordinates…] to read off data points.
(9) Record your results.
Mass Radius Speed Force
(Theo.)
Force
(Result)
kg m m/s kg ⋅ m⁄ N
(10) Plot - graph.
Plot - graph and verify the centripetal force is propor-
tional to the mass. Use the method of least squares if re-
quired. (Refer to the appendix of [Free Fall] experimental
manual.)
NOTE
Recorded data run has a default name Run#%1,
where %1 is an automatically generated run number. You
can change the name of each data run if required.
① Click [Data Summary] in the [Tools] palette
② Select [Show Sensor Data] tap.
③ Right-click on the run name of interest.
④ Select [Rename] from the pop-up list.
CAUTION
It is strongly recommended that you save the data file
with a different file name if you need to change the value
in the calculator. Changing makes all pre-measured
speed recalculated with the new value .
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 18 / 20
Experiment 3.
In this experiment, the mass and the speed are held
constant as the radius is varied. By lowering the Force
Sensor, the radius increases. As the radius increases, the
fixed mass must be moved to a matching radius to balance
the rotating arm.
(1) Follow the equipment setup instruction.
[Setup 1. Equipment Setup] on page 6
(2) Follow the software setup instruction.
[Setup 2. Software Setup] on pages 7-12
(3) Set the mass.
Choose any mass set.
(4) Set the speed. (You will finally set the speed in step (6).)
The (linear) speed is dependent to the radius of the circular
path of the mass, i.e. whenever you change the radius, you
have to adjust the voltage so the speed remains constant.
(5) Set the radius.
① Adjust the radius of the free mass to 9cm.
② Place the fixed mass at the same radius as the free mass
③ Enter 0.09 m for the radius in the calculator.
(6) Find the appropriate voltage output.
Click the [Record] button to monitor the speed of the mass.
You can monitor the speed of the mass in [Digits] display.
Fine-tune the [DC voltage] near 4V so you can find any volt-
age at which the speed shows easy value.
This speed is the target speed of this experiment.
In the later steps, you have to adjust the voltage to rotate
the mass under the same linear speed. (As the radius de-
creases, the voltage must be increased.)
In the pre-experiment, the linear speed was 2.0m/s in the
conditions of 9cm and 4.0V output. And then 7.2V was
supplied to rotate the mass with 2.0m/s in the condition of
5cm. (Required voltages depend on your motor status.)
You should choose the voltage between 3V and 9V. The
motor may not work in a lower voltage than 3V, and could
make a noisy vibration in a greater voltage than 9V.
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 19 / 20
(7) Measure the centripetal force.
If you have any useless data during monitoring the speed in
the previous step, delete it using [Delete Last Run] or drop-
down menu in the [Controls] palette.
In the condition of the voltage as you set in the step (6),
begin recording data.
(8) Stop data collection.
Click the [Stop] button to stop data collection.
(9) Change the radius.
Adjust the radii of the masses to 8cm.
Change in the [Calculator] to 0.08 m .
(10) Repeat measurement.
In the condition of 8cm, you must adjust the output
voltage so the speed shows the predetermined value in the
step (6).
Repeat measurement for R 9, 8, 7, 6, and 5cm.
(11) Record your results.
Mass Radius Speed Force
(Theo.)
Force
(Result)
kg m m/s kg ⋅ m⁄ N
(12) Plot - 1⁄ graph.
Plot - 1⁄ graph and verify the centripetal force is propor-
tional to the inverse of the radius. Use the method of least
squares if required. (Refer to the appendix of [Free Fall] ex-
perimental manual.)
CAUTION
You MUST save the data file with a different file name
for each data run in this experiment. Changing makes
all pre-measured speed in the prior step recalculated
with the new value .
General Physics Lab (International Campus) Department of PHYSICS YONSEI University
Lab Manual
Circular Motion and Centripetal ForceVer.20160315
Lab Office (Int’l Campus)
Room 301, Building 301 (Libertas Hall B), Yonsei University 85 Songdogwahak-ro, Yeonsu-gu, Incheon 21983, KOREA (☏ +82 32 749 3430) Page 20 / 20
Your TA will inform you of the guidelines for writing the laboratory report during the lecture.
Please put your equipment in order as shown below.
□ Delete your data files and empty the trash can from the lab computer.
□ Turn off the Computer.
□ Do NOT disassemble the equipment.
□ Keep the Mass Set, Mass Holder, Wire, and Bubble Level in the compartment box.
Result & Discussion
End of LAB Checklist