Physics 1401
Department of Physics and Geology
Kinetic and Potential Energy
Objective:
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Explore the relationship between Kinetic and Gravitational Energies
Analyze the importance of Kinetic Energy in falling objects.
Determine the energies involved of a free falling body
Purpose:
Understanding energy is the key to physics and the universe around us. It does not matter
what course work anyone studies there is always a component of energy. This lab will introduce
two type of energy and how to solve some problems with just calculating the energy involved.
Kinetic Energy is a very versatile equation to figure out how much energy a moving
object has. The term Kinetic means an object in motion. A Static object is one that is at rest (not
moving).
𝑲𝑬 =
𝟏
𝒎𝒗𝟐
𝟐
The above equation is used to solve the Kinetic Energy of an object. The m is the mass
of the object and v is the velocity of the object in motion. This raises the question of how is mass
irrelevant as explained above?
Created by Sjon Clinton
Physics 1401
Department of Physics and Geology
If you are solely looking at the kinetic energy of a moving object such as a car; then the
mass is very important. As we saw in the previous lab, change in kinetic energy is equal work
done. In this lab we will use kinetic energy to find how much potential energy an object has.
Another type of energy that we will study is called Gravitation Potential Energy.
𝑮𝑷𝑬 = 𝒎𝒈𝒉
Here m is still the mass, g is gravity (not to be associated with the acceleration due to
gravity because g is a scalar) and h is the maximum height of the object of your reference
frame.
GPE is the energy stored in an object while at rest in a gravitational field. At the
maximum height h, the object’s GPE will be a maximum. As the object moves towards the
center of the gravitation force the GPE will start to decrease while its kinetic energy increases.
What happens to the energy??
This change of energy is known as the Conservation of Energy.
Law of Conservation of Energy
Within some problem domain, the amount of energy remains
constant and energy is neither created nor destroyed. Energy
can be converted from one form to another (potential energy
can be converted to kinetic energy) but the total energy within
the domain remains fixed.
(Glen Research Center NASA)
\
In this experiment we will prove the conservation of energy by observing the interplay
between kinetic and gravitational potential energy. This is known as conservation of energy. This
means that the total energy in the system will not change. On the other hand, in a non-conservative
system, the total energy will not remain fixed.
Conservation of change in kinetic energy
∆𝑲𝑬 =
𝟏
𝒎𝒗𝟐 − 𝒎𝒈𝒉
𝟐
In our last lab we saw observed the relationship between kinetic energy and work done
by or on a system. In this lab, we will use the law of conservation to solve the same problems as
in the last lab. Let’s see if you still get the same results.
Created by Sjon Clinton
Physics 1401
Department of Physics and Geology
Materials:
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(1) Pasco Scientific Rotary Motion Sensor CI-6538
(1) Pasco Scientific Pendulum Accessory Me-8969
(2) Pasco Scientific 45cm Stainless Steel Rod ME-8736
(1) Pasco Scientific Multi-Clamp ME-9507
(1) Pasco Scientific Table Clamp ME-9972
(1) Digital Scale
(1) Meter Stick
Procedure:
1) Gather above equipment
2) Attach the table clamp to the table.
3) Insert 1 (one) steel rod into the vertical (up and down) groove
on the table clamp.
4) Tighten the rod into place.
5) Attach the multi-clamp to the vertical rod.
6) Tighten multi-clamp to vertical rod
7) Insert 1(one) steel rod into the horizontal groove of the multiclamp
8) Tighten the rod to the multi-clamp
9) Attach the pendulum accessory to the rotary motion sensor
by removing the bolt located on the pulley. DO NOT
LOOSE THIS SCREW, YOU ARE RESPONSIBLE
FOR THE EQUIPMENT.
10) On one end of the pendulum is a small hole.
11) Insert the long screw into the hole and attach the pendulum
to the pulley.
12) Slide the Rotary Motion Sensor to the horizontal rod to 10cm from the
multi-clamp.
13) Tighten the Rotary Motion Sensor to the rod.
14) Insert the YELLOW RCA cable into digital input
1.
15) Insert the BLACK RCA cable into digital input 2.
16) Open the Capstone folder located on the computer desk top.
17) Open the Capstone File labeled KE GPH Part 1.
Part I
Created by Sjon Clinton
Physics 1401
Department of Physics and Geology
18) Determine the mass of 1 (one) pendulum mass using the digital scale
19) Attach 1 (one) Pendulum mass to the bottom of the pendulum.
20) Swing the pendulum up to approximately 45ºfrom the table and hold it
there.
21) Click the
button in capstone
22) Release the pendulum so that it will fall freely and swing back and forth.
23) The timer will automatically stop after 3 min.
24) Once the time has stopped in capstone stop the pendulum from swinging.
25) Repeat steps (20-24) with the pendulum at 90º
26) In the capstone file, all the 90º tabs need to be adjusted to show RUN 2.
27) On the 1 Mass Angle 90º click the
button to select RUN 2.
28) Repeat step (27) for the rest of the graphs at 90 º
29) Print the comparison graphs in the landscape mode.
30) Leave the capstone file OPEN. DO NOT CLOSE THIS AS YOU WILL
LOOSE ALL YOUR DATA!!!!! YOU WILL NEED THE DATA TO
FILL IN THE FIELDS IN EXCEL!!
Created by Sjon Clinton
Physics 1401
Department of Physics and Geology
Part II
31) Open the capstone folder on the desktop.
32) Open the capstone file labeled KE GPH Part II
33) Determine 2 (two) pendulum masses using the digital scale
34) Attach 2 (two) Pendulum masses to the bottom of the pendulum.
35) Swing the pendulum up to approximately 45ºfrom the table and hold it
there.
36) Click the
button in capstone
37) Release the pendulum so that it will fall freely and swing back and forth.
38) The timer will automatically stop after 3 min.
39) Once the time has stopped in capstone stop the pendulum from swinging.
40) Repeat steps (31-35) with the pendulum at 90º
41) In the capstone file, all the 90º tabs need to be adjusted to show RUN 2.
42) On the 1 Mass Angle 90º click the
button to select RUN 2.
43) Repeat step (27) for the rest of the graphs at 90 º
44) Print the comparison graphs in the landscape mode.
Part III
45) Open the excel file titled KE GPE (student)
46) Column 1 is the points in time that the measurements will be taken to
solve for KE GPE
47) In the angle column you will expand the graph labeled angle and expand
the X-Axis to each time value requested. Insert that angle into the table.
48) The height column will automatically be filled in after you put the angle
in.
49) On a separate sheet of paper calculate both the Gravitational Potential
Energy and the Kinetic Energy. DO NOT HAVE EXCEL DO THE
MATH!
Created by Sjon Clinton
Physics 1401
Department of Physics and Geology
50) Print both pages of the excel sheet to be turned in with your comparison
graphs.
51) Remove the pendulum from the rotary motion sensor, the screw will not
come out of the rod!
52) Replace the original screw back into the rotary motion sensor.
53) You are responsible for any missing parts!
54) Return all equipment to proper place.
Questions:
(1) You drop a ball from the roof of the library with a mass of .20kg at height of 30m;
what is the velocity of the ball at impact with the ground?
(2) What is the Potential and kinetic energy half way through the free fall in question (3)?
(3) At what point is the Potential Energy at a maximum?
(4) At what point is the Kinetic Energy at a maximum?
(5) How important is the mass in determining the KE and GPE in this experiment. What
would happen if we double the mass or quadruple the mass?
Created by Sjon Clinton