Transformation of Mechanical Energy

A Laboratory Report Presented to:

Dr. Maria Cecilia D. GlavezDepartment of Physics

De La Salle University-Manila

In Partial Fulfillmentof the Requirements of the Course

LBYENVP A63A

By:Kaira L. Sy

February 20, 2013

I. Introduction

Background Information, Theories and Concepts

The energy acquired by the objects upon which work is done is known as mechanical

energy (ME). Mechanical energy is the energy that is possessed by an object due to its motion or

due to its position. Mechanical energy can be either kinetic energy (energy of motion) or

potential energy (stored energy of position). Objects have mechanical energy if they are in

motion and/or if they are at some position relative to a zero potential energy position (for

example, a brick held at a vertical position above the ground or zero height position). A moving

car possesses mechanical energy due to its motion (kinetic energy). A moving baseball possesses

mechanical energy due to both its high speed (kinetic energy) and its vertical position above the

ground (gravitational potential energy). A barbell lifted high above a weightlifter's head

possesses mechanical energy due to its vertical position above the ground (gravitational potential

energy). A drawn bow possesses mechanical energy due to its stretched position (elastic potential

energy).

Objectives

The objectives of the activity is:

To learn about gravitational potential energy and kinetic energy of a dynamic cart along an

inclined plane.

To investigate the transformation of mechanical energy of the cart.

To investigate how the gravitational potential energy and the kinetic energy is affected by

increasing the release height of the cart keeping the mass of the cart constant.

To investigate how the gravitational potential energy and the kinetic energy is affected by

mass of the cart keeping the height constant.

To investigate if the mechanical energy of the dynamic cart along an inclined plane is

conserved.

Hypothesis

The higher the incline, the faster the acceleration of the cart and more kinetic energy is used. The

lower the incline, the slower the acceleration of the cart and potential energy is more evident.

II. Method

In this activity, the cart is placed 20 cm from the position sensor and released from rest as

shown in figure 1. The position sensor is attached to Spark Vue and as the cart moves along the

track, its position, velocity, and acceleration is recorded. Data acquisition is stopped just before

the cart reached the bumper. From the initial and final positions and the constant acceleration,

the PE and KE of the cart can be calculated. The experiment will have two parts. The first part

involves increasing the release height while maintaining a constant mass of the dynamic cart,

where as the second part involves increasing the mass of the cart while maintaining a constant

release height.

III. Materials Used & Experimental Set up

1. The Cart 2. Iron Stand3. Position Sensor4. Cart Stopper5. Dynamic Track6. Spark Vue

IV. Data

Observations in a Data Table or Chart

Graph:

The lower the incline, the longer the time it takes for the cart to reach the end.

Charts:

CalculationThe computer made the calculation automatically as the graph was made.

V. Analysis

When the cart is going down new energy, kinetic energy, it created right before the cart

hits the ground. Then there is a loss of energy, potential energy, when the cart hits the ground.

The cart also has mechanical energy as it rolls down the hill. This also has rolling friction, and

motion. Rolling friction occurs when the cart rolls down the ramp and on the floor.

It has motion from the minute it is acted upon by an unbalanced force. In this case it's

related to Newton's 1st law. When the kart is in motion, it gains speed. But then, it also has

acceleration as it is released and goes down the ramp, because it gains speed. This also gives it

momentum, because the cart gains speed, which also gains momentum. There is also air

resistance, which can also be fluid friction, because air resistance is, the fluid friction

experienced by objects falling through the air. In this case as the cart gains speed and

momentum, then goes down the ramp. Whenever there is motion, that object has speed and has

been acted upon by an unbalanced force.

Newton's 2nd law, Acceleration depends on the object's mass and on the net force acting

on the object. When the cart goes down the ramp, gravity makes the kart speed up. The higher

the ramp is put, the greater its speed becomes by the time it reaches the bottom of the ramp.

Newton's 3rd law, if one object exerts a force on another object, then the second object exerts a

force of equal strength in the opposite direction on the first object. Since the cart is on a ramp the

ramp has to support the weight of the cart. If the wheels stop the cart from going off course too

much, then by exerting a controlling force, the cart will stay on the track until acted upon by an

unbalanced force.

VI. Conclusion

To conclude the experiment, the relationship of kinetic energy and potential energy

with the total mechanical energy is that the sum of kinetic energy plus potential energy is

equal to the total Mechanical Energy.

Reflecting to the experiment, Mechanical energy is always evident. As we have

defined it as the sum of the two basic energies. Results may change prior to the external

energy acting upon the object.

VII. Discussion Questions

1. What kind of energy did the cart have at its released point?

Potential Energy

2. How did the cart obtain that energy?

The cart obtained the energy due to its position, also because it was at rest.

3. What kind of energy/energies did the cart have as it was rolling down the ramp?

Kinetic Energy

4. What happens to the velocity of the cart as it slides down the incline plane? How

does this affect the kinetic energy of the cart? How about its potential energy?

The velocity of the cart increases as it slides down the incline plane. Kinetic

energy increases, as the direction of the cart is linear. There is no Potential

energy until the cart stops at the end.

5. As the height of the ramp increases, what happened to:

a. The acceleration of the cart?

As the height of the ramp increases, the acceleration increases also.

b. The initial potential energy of the cart?

Zero

c. The final kinetic energy of the cart?

The kinetic energy also increases. Driven from the formula:

6. Based from your data,

a. What are the initial mechanical energy and the final mechanical energy of the cart?

The initial mechanical energy always has a value and can never be zero. Even

when it is stationary at one place or in motion in another, an amount is always

existent. The final mechanical energy of the cart depends on how steep the

incline is. The higher the incline the higher the amount of the mechanical

energy, the lower the incline, the lower the amount of mechanical energy.

b. How do the values of the initial mechanical energy and final mechanical compare to

the the initial potential energy and final kinetic energy?

The only difference between the two is the initial energy. Since the initial

potential energy is zero, it differs with the result of the initial mechanical

energy. Also in other cases, if external forces influences the movement of the

cart the result of work done or mechanical energy may change prior to what

has happened.

7. How does this experiment demonstrate the transformation of Mechanical energy?

Mechanical energy is the energy that is possessed by an object due to its motion or

due to its position. Mechanical energy can be either kinetic energy (energy of

motion) or potential energy (stored energy of position). Objects have mechanical

energy if they are in motion and/or if they are at some position relative to a zero

potential energy position. In this case, the moving cart possesses mechanical energy

because of its motion (kinetic energy). The transformation of the energy occurs

when the cart is at rest from potential energy, moves down the incline in motion to

kinetic energy.

VIII. References http://www.physicsclassroom.com/class/energy/u5l2bb.cfm

http://www.lightandmatter.com/html_books/me/ch13/ch13.html

http://www.physicsclassroom.com/mmedia/energy/ie.cfm

http://en.wikipedia.org/wiki/Mechanical_energy