Kinetic Energy (B)
Definitions of Energy
Kinetic Energy
Kinetic energy is the energy of motion. The following two experiments were designed to explore
whether speed or mass plays a bigger role in determining the amount of kinetic energy. Experiment
1 was designed to test how speed affects kinetic energy. The kinetic energy is calculated using a
mass of 1,200 kg (mass of an average car) traveling at various speeds.
The equation for calculating the kinetic energy of an object is KE =
1 2
mv .
2
KE = the kinetic energy of the object. It is measured in the energy unit of joules (J).
m = the mass of the object in kilograms (kg).
v = the speed of the object, measured in meters per second (m/s), which must be squared.
Note: 1 Joule = 1 kg x (m/s)2.
Complete the table for Experiment 1 and find the kinetic energy of the car at different speeds. In
this experiment, mass is constant, which means that mass does not change.
Experiment 1: Kinetic Energy of a 1,200kg Car at Different Speeds
Mass of Car
Speed of Car
Kinetic Energy
1,200 kg
2.78 m/s
1.
1,200 kg
5.55 m/s
2.
1,200 kg
8.33 m/s
3.
1,200 kg
11.11 m/s
4.
1,200 kg
13.89 m/s
5.
1,200 kg
16.67 m/s
6.
1,200 kg
19.44 m/s
7.
1
Kinetic Energy (B)
Definitions of Energy
Experiment 2 was designed to test how mass affects the kinetic energy of the car. The kinetic
energy was calculated using different masses of cars traveling at the same speed.
The equation for finding the kinetic energy of an object is KE = 1 mv 2 .
2
KE = the kinetic energy of the object. It is measured in the energy unit of joules (J).
m = the mass of the object in kilograms (kg).
v = the velocity of the object in meters per second (m/s). This value must be squared.
Note: 1 Joule = 1 kg x (m/s)2
Complete the table for Experiment 2 and find the kinetic energy of different masses of cars
traveling at the same speed. In this experiment, speed is constant, which means that speed does
not change.
Experiment 2: Kinetic Energy of Cars of Different Masses Traveling 2.78 m/s
Mass of Car
Speed of Car
Kinetic Energy
900 kg
2.78 m/s
8.
1,000 kg
2.78 m/s
9.
1,100 kg
2.78 m/s
10.
1,200 kg
2.78 m/s
11.
1,300 kg
2.78 m/s
12.
1,400 kg
2.78 m/s
13.
1,500 kg
2.78 m/s
14.
2
Kinetic Energy (B)
Definitions of Energy
15. Draw a line graph that represents the relationship between speed and kinetic energy in
Experiment 1. Make sure to give the graph a title and label the x and y axes, including units.
Remember that in this experiment, mass is constant.
Title: _______________________________________________________
300,000
280,000
260,000
__________________________
240,000
220,000
200,000
180,000
160,000
140,000
120,000
100,000
80,000
60,000
40,000
20,000
0
2
4
6
8
10
12
14
16
18
20
______________________________
3
Kinetic Energy
Definitions of Energy
16. Draw a line graph that represents the relationship between mass and kinetic energy in
Experiment 2. Make sure to give the graph a title and label the x and y axes, including units.
Remember that in this experiment, speed is constant.
Title: _______________________________________________
6500
6000
_____________________________________
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
900
1,000
1,100
1,200
1,300
1,400
1,500
1,600
____________________________
17. In your own words, describe what the data from the graphs tell you about mass, speed, and
kinetic energy. Which property seems to have a greater effect on an object’s kinetic energy:
speed, mass, or both?
4