Holy Child Educational Center, Inc.

San Jose, Iriga City S/Y 2013-2014

(Science Investigatory Project)

Members:

Luzille Rodriguez

Abigail Gorgonia

Nikka Estallo

Justin Ayubo

Froilan Gentalian

Noelan Serrano

Submitted To:

Rolando B. Bancaso

Approval Sheet

Mdm. Maricee S. Bernal Adviser Date

Critic Date

Critic Date

Critic Date

Sir Rolando B. Bancaso Subject Area Head Date

Accepted as partial fulfilment of the requirements for the

Chemistry Subject.

Acknowledgement

We would like to extend our deepest gratitude to those who have, in one

way or another helped us complete this project.

First and foremost, to Angeli Nanali, for help given;

To Julie Ann Pontanares, and Nathaniel Lareza for all their guidance and

enthusiasm;

To all St. Peregrine family, thank you for the moral support;

To our family and friends, who had given us financial support;

To Vic Anthony Rodriguez, for the interpretation of our data;

To Engr. Hilario Gorgonia, for giving us the materials needed;

To Larnny Ibias, for providing reference books;

To Jessamae Agnas for the electronic devices our group needed;

To our physics teacher, Sir Rolando Bancaso, for the guidance and

To God, who always gives hope to our group.

Abstract

What keeps you in your seat of a giant loop-de-loop roller coaster?

Surprisingly, it is not the seatbelt but the seat! It works because of something

called centripetal force and it does much more than make a great roller coaster.

It keeps a satellite in orbit, you in your bicycle seat during a turn, and earth’s

revolution around the sun. Centripetal force is a great study that let people

understand those natural events.

I. Introduction

Sir Isaac Newton was a careful observer of the world around him. He

used mathematics and science to describe natural phenomenon which, at the

time, were not understood. Newton discovered that to get an object to move,

the object must experience a force that makes it move in a certain direction.

Once the object experiences this force, it is set in motion and will continue

this motion until it experiences an opposite force that causes the motion to

stop. You have felt this phenomenon when riding a roller coaster. When the

roller coaster starts moving, you rock backwards because your body wants to

stay in its stationary position, but after you move, if the roller coaster

suddenly stops, you will rock forward because your body wants to keep

moving forward at the same speed and direction. This example describes

what happens when you experience motion in a straight line.

In circular path and curves, newton realized that the object wants to

move away from the center of the circle. For example, when you are riding in

a loop-de-loop roller coaster. The tracks are moving in a circle, and we move

along with it, but what is keeping us in our seat? Gravity is a force that push

us down toward the ground, which may help us stay in our seat at the bottom

of the loop, but it probably does not help us stay in our seats at the top of the

loop! The force from our seatbelt may help us stay in our seat but centripetal

force is the one that is constantly pulling us towards the center of the loops.

Which force is the centripetal force when we ride in the loop-de-loop?

In this physics science project we will investigate the movement of

an object during circular motion and determine what the centripetal force is

that keeps the object moving in a circular way.

II. Review of Related Literature

The review of the literature for this study focuses on centripetal

force and its importance. The study focuses to the location of the force

when a certain circular motion happens. The research outcomes germane

to other studies such as newton’s first law of motion, gravity, forces

applied, and many more.

The centripetal force is directed inwards, from the object to

the center of rotation while centrifugal force is directed outwards; in the

same direction as the velocity of the object. Centripetal force occurs

everywhere so loads of experiments and activities can be done to visualize

or observe its existence.

Comparison of Centripetal force and Centrifugal force

Many researchers have proclaimed that centripetal and centrifugal

forces differ depending on the situation of an object undergoing motion in

a curve line or circular motion. Based from www.diffen.com:

Centrifugal Force Centripetal Force

Meaning: Tendency of an object

following a curved path to fly

away from the center of

curvature. Might be described

as “lack of centripetal force.”

The force that keeps an object

moving with a uniform speed

along a circular path.

Direction: Along the radius of the circle,

from the center towards the

object.

Along the radius of the circle,

from the object towards the

center.

Example: Mud flying off a tire; children

pushed out on a roundabout.

Satellite orbiting a planet

Formula: Fc = mv2/r Fc = mv

2/r

Defined by: Chistiaan Hygens in 1659 Isaac Newton in 1684

Centrifugal Force Centripetal Force

Is it a real

force?:

No; centrifugal force is the

inertia of motion.

Yes; centripetal force keeps the

object from "flying out".

Other experiments in connection with Centripetal force

The spinning penny, it shows the relationship of the size of the coin to the

time it spins, and it also proves that the centripetal force is a center seeking

force, (Steve Spangler). Bucket swing, defying gravity, ping pong challenge.

From www.afterschooltreats.com

Centrifugal Force doesn’t exist?

According from www.regentsprep.org centrifugal force doesn’t exist. It is

only the absence of centripetal force. An example is when a car is experiencing

a turn, a light object on the dashboard moves at the opposite direction of the

turn. The object moved because of the lack of friction or another object with

centripetal force not because of the centrifugal force.

III. Objectives of the Study

To investigate the movement of an object during circular motion.

To determine what the centripetal force is.

To know what factors affect centripetal force.

To help students gain knowledge about centripetal force.

IV. Statement of the Problem

Whenever an object moves in a circular path we know the object is

accelerating because the velocity is constantly changing direction. All

accelerations are caused by net force acting on an object. In the case of an

object moving in a circular path, the net force is a special force called the

centripetal force.

So a centripetal force is the center seeking force which means that

the force is always directed toward the center of the circle. Without this

force, an object will simply continue moving in straight line motion. This

study aims to determine this centripetal force and compare it with the

balancing force of gravity on a hanging object.

1. What is the relationship of mass, velocity, radius and the

centripetal force experienced by the object?

2. Is there other factors affecting Centripetal force that can be seen

in the study?

V. Hypothesis

If an object is in circular motion and something pulls it to the center

or holds it to retain in a certain position while experiencing the motion, then

the object is experiencing centripetal force.

If the object involved is heavy and if it undergone an increase in

velocity, then it needs a greater amount of centripetal force. If radius

increases the needed centripetal force decreases.

If circular motion can be horizontally or vertically, then both of it

has different effect to the amount of centripetal force because of gravity

and other forces.

If the object did not take the right amount of velocity and

centrifugal force and it has short radius, then if it is in horizontal circular

motion, it will acquire less centripetal force, and if it is in vertical circular

motion, it may fall due to powerful gravity than the centripetal force.

VI. Significance of the Study

Anytime anything goes round in a circle, or even just a bit of a curve,

a centripetal force must have operated. These forces are just the ordinary,

everyday forces like gravity, tension, electric and magnetic forces which get

called "centripetal" when they make things move in circles. So their practical

use is endless - keeping electrons moving about atoms, keeping planets

moving round stars and stars moving round galaxies and cars moving round

corners and turbine blades revolving - you can come up with dozens more.

Centripetal force is important because:

It helps drivers avoid car accidents.

It gives ideas for useful appliances; one example is the

washing machine.

It identifies the right road design to avoid car accidents

It helps ensure safety at amusement parks and carnivals

by having the right design of rails.

VII. Scope and Limitation

Our study focuses only to some factors affecting centripetal

force, these are the following: mass, velocity radius, and area

This study is applied to horizontal circular movement.

Its main focus is the centripetal force even though other forces

are evident in the study.

We focused more on the observable components of the

factors affecting Centripetal force, if new factor will be

observed in the experimentation, No formula can be

formulated in the study.

VIII. Research and Design

Materials

Stove

Cooking pot

Measuring cup

Tap water, normal temperature and cold

JELL-O packages (2). Use two very different colors of JELL-O, both light-colored (like cherry and lime).

Stirrer

Plastic cups, clear (6) have extra cups for mistakes)

Permanent marker

Calculator

Refrigerator

Timer or clock

Marbles (3 small and light in weight and big heavier) (weigh the 2 kinds of marbles and convert to kg and take note)

Oven mitt

Scissors

String (at least 2 yards long)

Electrical tape or duct tape

Optional: Flashlight

Lab notebook

Methodology

Making the Centripetal Force Test Chambers

In this part of the science project, you will make 6 centripetal force test chambers using JELL-O, cups, and marbles. You will want to make more than one to have replicates, or copies, of your data.

1. Make a package of JELL-O by following the instructions on the box, except use more cold water than is recommended.

Making JELL-O using 3.5 cups of water will make it less thick and more liquid. This will make it easier for the marble to move when you test it later.

a. On the stove in the cooking pot, have an adult help you warm the appropriate amount of water according to the instructions on the box.

b. Continue following the box's instructions by adding the JELL-O mix to the warm water. Stir the JELL-O mix in the water for 2 minutes while keeping the pot on the hot burner.

c. After stirring for 2 minutes, the JELL-O should be completely dissolved and no particles of JELL-O powder should be visible. It should look clear.

d. Take the JELL-O off of the hot burner and add 1.5 times the amount of cold water that is recommended on the box's instructions. Use cold tap water and stir it in as it is added.

i. For example, if the instructions say to use 1 cup of cold water, use 1.5 cups of cold water instead.

2. Pour the JELL-O into six of the plastic cups, filling each cup a little less than halfway full. These will be your centripetal force test chambers.

a. Use a permanent marker to label these cups #’s 1,3,5 for small marbles and #’s 2,4,6 for big ones.

3. Place the cups in the refrigerator and refrigerate them for 4 hours. a. Because you used more water than is recommended in the box's

instructions, the JELL-O will not be very firm after 4 hours, but it should be firm enough to support the marble in the next step.

4. In each cup, place a marble on the top of the JELL-O in the center of the cup. Gently press into the JELL-O just until the marble is secure and will not move around.

5. Make the second batch of JELL-O by preparing it as you did in step 1. The second batch must be different in color with the first batch.

6. After adding the cold tap water to the JELL-O, place an oven mitt in the refrigerator and have an adult help you place the pot with the JELL-O on the oven mitt. Refrigerate the pot of JELL-O for 30 minutes.

a. This second batch of JELL-O will be added to the JELL-O already in the plastic cups. However, if the second batch of JELL-O is not refrigerated before it is added, it may be too hot and melt the first layer of JELL-O.

7. After refrigerating the pot of JELL-O, slowly and carefully pour the JELL-O into the cups, covering the first layer of JELL-O and the marble, until the cups are almost full. Leave about 2.5 centimeters (cm) (1 inch) at the top of the cups.

a. It is important to slowly and carefully pour the second layer of JELL-O on top of the first layer because otherwise the second layer may damage the first layer.

b. Do not worry if the two layers of JELL-O mix together a little where they meet. However, check to make sure that the marble stays

roughly in the middle, between the two layers. Do not use any cups in which the marble is not near the middle.

i. If multiple cups have marbles that are not near the middle, try repeating steps 1-7 but use less cold water in step 1e, such as 1.25 cups instead of 1.5 cups.

c. Your cups should look similar to the one in Figure 1 below, although your layers of JELL-O may be different colors.

Figure 1. Once you have poured two layers of JELL-O into your cups, they should look similar to

the one, with the marble in between the two layers.

1. Place the cups in the refrigerator and refrigerate them for 4 hours. 2. While your JELL-O solidifies, prepare your centripetal force generator.

You will be testing your test chambers inside of the generator. a. Take an empty plastic cup and use the scissors or any sharp object

to make a small hole about 2.5 cm (1 inch) from the top rim of the cup. Make a second hole on the opposite side of the cup.

b. Put a small piece of electrical tape or duct tape on the edge of the cup, just above each hole. Fold over the tape so it is on the outside and inside of the cup, but not blocking the holes. This will help prevent the string, which you will attach next, from detaching.

c. Attach the string to the top of the cup, tying one end of the string through one of the holes at the cup's top and the other end through the other hole.

d. Your cup should now look like the one in Figure 2 below. This cup will be your centripetal force generator. Test to make sure that the string is strongly attached to the cup by holding on to the string and pulling down on the cup.

Figure 2. Prepare your centripetal force generator cup, as shown here, by making two holes in the

top of the cup, placing electrical or duct tape above the holes, and tying string through the holes.

e. Cut two pieces of strings. One short and one long. Tie both of it tightly at the center of the semi-circle string attached to the centripetal force generator.

Testing the Centripetal Force Test Chambers

1. After refrigerating the cups, take #1 of your test chambers and place it in the centripetal force generator by stacking the plastic cup with the JELL-O into the plastic cup with the string.

a. Do not use any cups in which the marble is not near the middle. If multiple cups have marbles that are not near the middle, try repeating the section titled "Making the Centripetal Force Test Chambers" but this time use less cold water when making the JELL-O in steps 1e and 5, such as 1.25 cups instead of 1.5 cups.

2. Now hold the short string and quickly twirl the cup around for 5 sec. Another member should count the number of complete circle made. You must spin the cup hard and fast to get enough centripetal force for the marble to move!

3. After 5 sec. stop spinning and separate the two cups. Multiply the number of complete circle made to the circumference. Formula: 2 (length of the short string)

4. Then divide to 5 sec. The quotient is the velocity. 5. Observe the JELL-O, and the position of the marble relative to the two

different colors of JELL-O. Remember that the marble started out right at the dividing line between the two colors. Make observations, drawings, and record data in a table similar to Table 1. Put it in your lab notebook

a. If you have trouble locating the marble, try backlighting the marble by shining a flashlight through the back of the cup, toward you.

Test

chambers

mass of

the marble

(kg)

Velocity

(m/s)

Radius

(m)

Centripetal

force (N)

Where did

the marble

move to?

Other

observations

#1 Small Same as #2 Short

#2 Big Same as #1 Short

#3 Small Higher to #1 Short

#4 Big Same as #3 Short

#5 Small Same as #1 long

#6 Big Same as #1 long

Table 1. In your lab notebook, make a table like this one to record your observations and data.

b. If the marble did not move, the JELL-O may be too firm. First try spinning it again with the same procedure but faster this time. The velocity will surely change. Do the computation again. If the marble has still not moved, either let the cups sit out at room temperature overnight to soften the JELL-O or repeat the section titled "Making the Centripetal Force Test Chambers" but this time use more cold water when making the JELL-O in steps 1e and 5.

6. Repeat steps 1-4 with #2 test chambers. The velocity should be the same with #1 test chamber

7. For test chamber #3 and #4 repeat steps 1-4 but with higher velocity. Let your strongest member do it. The velocity of #3 and #4 should be the same.

8. For test chamber #5 and #6 repeat steps 1-4 but use the longer string. The velocity of test chamber #’s 5 and 6 should be the same with #’s 1 and 2.

9. Did you notice any patterns of movement? Did the marbles always move in the same direction? Did they move in the direction you thought they would? How far did they move? What is the relationship of the mass, velocity and radius to the centripetal force? Where do you think the centripetal force is occurring?

a. Based on where the marbles went during circular motion, what do you think is the centripetal force that keeps the marbles moving in a circular way, and prevents them from flying off in a straight line?

b. For more accurate result, video every spinning.

IX. Results and Discussion Test

cham

bers

Description

of the area of

the marble

mass

of the

marble

(kg)

Velocity

(m/s)

Radius

(m)

Centripetal

force (N)

Where did

the marble

move to?

Other

observat

ions

#1 Same as 3 and 5 0.0047 2.58 0.158 0.198

#2 Same as 4 and 6 0.0207 2.58 0.158 0.872

#3 Same as 1 and 5 0.0047 4.17 0.158 0.517

#4 Same as 2 and 6 0.0207 4.17 0.158 2.278

#5 Same as 1 and 3 0.0047 2.58 0.31 0.101

#6 Same as 2 and 4 0.0207 2.58 0.31 0.444

#7 Same as 2, 4 & 6 0.0414 2.58 0.31 0.889

Computations:

Circumference Short String Circumference Long String

= 2(3.1416) (0.158) =2(3.1416)(0.31)

# of circles made in 5 sec.

Test Chambers #1 & #2 = 13, Test Chambers #3 & #4 = 21, Test Chambers #5 & #6 = 13

Velocity

Formula: (Circumference)(# of circles made in 5 sec.)/ 5 sec. Centripetal Force Formula: = mv2/r Legend: m = mass, v = velocity, r = radius

Observations 1) Test chamber #1, the marble moved downward and a little sideward, it is

already in the estimated middle of the bottom color. 2) Test chamber #2, the marble moved downward, but higher than #1. This

chamber has the bigger and heavier marble. 3) Test chamber #3, the marble moved downward and sideward. It reached the

bottom of the plastic cup. 4) Test chamber #4, the marble moved downward. Compared to test chamber

#2, #4 is lower. #2 and #4 contain marbles with same size and mass. 5) Test chamber #5, the marble moved a little downward. 6) Test chamber #6, the marble, at first sight didn’t seem to move. But when

inspected keenly, it moved a little. 7) Test chamber #7, the marble moved to the middle side of the lower color of

the jell-o 8) No marble moved upward 9) Test chambers # 2,4,6 with heavier marbles have higher centripetal force

compared to test chambers #1,3,5 10) Test chamber #4 had the highest Centripetal force 11) Test chamber #3 had a higher Centripetal force compared to other

chambers with same marble. 12) Test chambers #5 and #6 have lower centripetal force compared to #1

and #2 considering these chambers having same velocity. 13) Test chamber marble #7 is heavier to test chamber marble number #6

and it moved really downward compared to #6. But Test chamber marble #2, #4 and #6 is heavier to #1, #3, and #5 and yet #1, #3, and #5 moved more downward than those with heavier marbles.

X. Conclusion

We therefore conclude that Mass, velocity, and radius are all related

when you calculate centripetal force. Also Area of the object experiencing the

net force affects the needed amount of centripetal force needed. The

Centripetal force in the experiment is located on the Jell-o, the plastic cup and

the rope.

Increasing mass, increasing Centripetal force needed and vice versa.

Increasing speed or velocity, increasing Centripetal force needed and Vice

versa

Decreasing radius, increasing Centripetal force needed and vice versa

Area of the object experiencing the net force affects specific objects

having the centripetal force.

Recommendation

We would like to recommend this further analysis about Centripetal force. It

can help to the learning about centripetal force and the three factors affecting

it.

XI. Bibliography http://www.stevespanglerscience.com/lab/experiments/spinning-penny

http://www.diffen.com/difference/Centrifugal_Force_vs_Centripetal_Force

http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p018.shtml#background

http://wiki.answers.com/Q/What_are_some_practical_applications_of_centripetal_force