Experiment 1 by Bayot, Lim, Uy

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De La Salle UniversityCollege of Education

Science Education Department

PHY 583MEarth and Environmental Science

Experiment # 1

WORK AND KINETIC ENERGY

Members: Bayot, Joysol

Lim, Perlita

Uy, Roxanne

Prof: Dr. Cecil Galvez

Class Period: Sat, 8:00 am11:00 am

Date performed: 1/26/13


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I. INTRODUCTIONA. BACKGROUND INFORMATION/THEORY AND CONCEPTS

Work is the change in energy from one form to another by means of an external force.

When work is done on an object, the object is said to have either gained or lost a certain

amount of energy of a particular type. Hence the units of work are the same as the unitsof energy: joules. Work is considered to be positive, negative, or zero in value,

depending on the direction of transfer.

To calculate the work done, the distance travelled and the net force acting on the object

must be determined.

W = Fnet .d

Fnet = M.a

Change in kinetic energy states that the work done by the resultant external force on abody is equal to the change in the kinetic energy of the body.

KE = 1/2 Mv2

Wtotal=K = KfKi

The result is called Work-Kinetic energy theorem.

The purpose of this Activity is to calculate the work done by a constant force and to

compare the work done and the change in kinetic energy.

B. OBJECTIVES

This activity aims:

To examine and calculate the work done on the dynamics cart by a constantforce.

To compare the work done and the change in kinetic energy.C. HYPOTHESIS

If an external force is applied on a body with displacement, then a work is done.


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II. METHODSTART

SECURE MATERIALS

PREPARE SET-UP

USE SPARK COMPUTER PROGRAM

COLLECT DATA NEEDED FOR THE EXPERIMENT

GET THE ACCELERATION OF THE CART

CALCULATE WORK DONE

CALCULATE KINETIC ENERGY

IS THE DATA

COMPLETE

AND N

ACCURATE?

Y

FIX SET UP

MAKE FURTHER STUDIES

END


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III. Materials Used and experimental set-up


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IV. DATAa. OBSERVATIONS in a DATA TABLE or CHART

Table 1. Shows the hanging mass, minimum distance, maximum distance, and the distance

(difference between minimum and maximum distance) of the 3 runs of the cart

Table 2. Shows the hanging mass and the acceleration of the 3 runs of the cart

Table 3. Shows the hanging mass, distance, acceleration, force and work of the 3 runs of the cart


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Table 4. Shows the hanging mass and the acceleration of 3 runs of the cart

Table 5. Shows the hanging mass, distance, acceleration, force and work of the 3 runs of the cart

Table 6. Shows the hanging mass and the final velocity of the 3 runs of the cart


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Table 7. Shows the hanging mass, final velocity, work and change in kinetic energy of the 3 runs

of the cart

Table 8. Shows the mass of dynamic cart, hanging mass, distance, acceleration of the cart, and

the force of the 3 runs of the cart


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b. GRAPHS

Figure 1.Position versus Time of the 3 runs

Figure 2.Velocity versus Time of the 3 runs


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Figure 3.Force versus Hanging Mass of the 3 runs


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Figure 4.Work versus Force of the 3 runs


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Figure 5.Work versus Change in Kinetic Energy of the 3 runs


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c. CALCULATIONSc.1 Final Velocity

Vf = Vi + a * t

where:Vf = final velocityVi = initial velocity

t = change in time

a = acceleration

c.2 Force

f = m x a

where:

f = Forcem = massa = acceleration

c.3 Work

W= Fnet d = F cos

where:

Fnet = Net Forced = distance

c.4 Acceleration

a= v

t

where:

v = change in velocity

t = change in time


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c.5 Kinetic Energy

KE = mv 2

where:

KE= Kinetic energym = mass

v = velocity

V. ANALYSISBased from Figure 2, it shows that the velocity versus time graph moves along a

straight line, making it linear in shape and is constant. Given that it shows the slope of

velocity with respect to time, it represents the physical quantity of acceleration. It

also means that acceleration on the graph is constant

The initial kinetic energy of the cart is zero (0). Any object that is not in motion will

have an initial kinetic energy of zero.sa

Figure 3 shows that the graph moves along a straight line, thus making its shape a

linear one. The acceleration of an object depends on the net applied force, and the

mass. In this experiment, the hanging mass determines the net force acting on thesystem of both masses. This net force accelerates both the hanging mass and the

carts mass; the cart mass is accelerated horizontally, and the hanging mass isaccelerated downward.

Figure 4 shows that the graph shows a linear relationship between work and force.

Force is essential to perform work. When the point of application of the force getsdisplaced, then force is said to have performed work. Based on the graph and the

equation, W = Fnet . d, work is directly proportional to force.

Figure 5 shows a graph that is not linear in shape, due to some error that can be

anticipated while performing the experiment. However relationship between work

and change in kinetic energy is applicable when conservative forces act on a system.This relationship is known as the Work Energy Principle. So Work may be definedas a change in Kinetic Energy


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VI. CONCLUSIONWork done by applied force is equal to the product of F, the component of Fa in the

direction of the displacement, and change in d, the distance through which the mass

moves.

Theoretically work done must be equal to change in kinetic energy. But the results of

the activity/experiment would not yield the theoretical aspect since in the real setting

some forces cannot be neglected like friction.

VII. ANSWERS TO QUESTIONS1-2. Draw the cart and then indicate the forces acting on the cart. Which force/s does/ do

not work on the cart? Why?

Where:

Fnorm = normal force

Fgrav = gravitational force = M*g

Fapp = applied force (tension on the string) = m*g

fk = kinetic friction

3. In this experiment, 2 graphs were recorded. These are the position vs time graph, and

velocity vs time graph.

a.What are the shape of the position vs time graph and the velocity vs time graphThe graphs move along a straight line, thus making it linear in shape.

Fnorm

Fgrav

Fappfk


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b.What do these graphs tell you about the carts position, velocity, and acceleration as thecart moves from its initial position to the final position?

c.What physical quantity does the slope of the position vs time graph represents?The slope of position with respect to time represents velocity of the object.

d.What physical quantity does the slope of the velocity vs time graph represents?The slope of velocity with respect to time represents acceleration.

4. If you increase the hanging mass, what do you think will happen to the following

quantities?

a.Acceleration of the cartAcceleration of the cart will increase since there is an rise in pressure in order to move theobject.

b.The net force of the cartLike acceleration, net force will rise since there is an increase in the hanging mass.

c.The work done on the cartWork done will increase since variables affecting work increased.

d.The change in kinetic energy of the cartChange in kinetic energy will also increase because it is proportional to the rise of otherfactors.

5. What does it mean if the slope of the x vs y graph is equal to 1?

When the slope of the x vs y graph is equal to 1 it means that change in work done is equal to

change in kinetic energy.

6. What is the value of the slope of work vs KE graph? Is it really equal to 1? What does

it tell you about the relationship between work and KE?

Generally, the work done on a body is equivalent to the change in kinetic energy of that body.

Since the body is initially at rest, the kinetic energy of the dynamics cart depends only on itsfinal kinetic energy.


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The slope of the graph is equivalent to 1.16 using the formula, m= (y1-y2) / (x1-x2). The value

of the slope tells that there is a slight difference between the obtained work and the kinetic

energy. Based from the data, the shorter distance travelled by the cart with the 0.020 kg

hanging mass is the cause of the sudden decrease in final velocity hence, the decrease inkinetic energy.

7. What do you think is the reason why the work done and KE are not really equal to one

another?

Work done and change in kinetic energy are not equal to 1 since there are other variables to

consider when computing for it. It will only be equal to each other if these other variables

will be neglected.

VIII. REFERENCES1. Heuvelen. University Physics, 6

thedition. 2004

2. Young and Freedman. University Physics, 11th

edition. 2005

3. Hewitt. Conceptual Physics. 2005


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Experiment 1 by Bayot, Lim, Uy

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