WORK, FORCE, & ENERGY
A LABORATORY INVESTIGATION
Dr. Mike Mahan
Assistant Professor, Science Education
Armstrong Atlantic State University
11935 Abercorn Street
Savannah, GA 31419
Dr. Mahan has taught General Biology at Ball State University and at Kean University and Elementary and Secondary Science Methods in the College of Education. Dr. Mahan is a Licensed High School Biology Teacher in the state of New Jersey, Georgia, and Indiana.
WORK, FORCE, ENERGY:
Connecting Biology and Physics
In science education, there is a golden opportunity to make real world connections with information that is current and relative to the student. Science Educators teach POWER, FORCE, ENERGY, NUTRITION, & WORK as components of Physical Science and/or Physics, Biology, Chemistry, and Health. The appropriate timing for this lab would be during a discussion on force, energy, or work in a Physical Science setting, during a discussion of energy conversion in the Biology setting and during a Human Nutrition discussion in Health.
Students will be able to calculate energy used to move their mass.
Students will gain an understanding that it takes energy in various forms to do work.
Students will understand that human movement (work) requires energy in the form of a fuel (food) to be carried out.
In Physical Science/Physics, make the connection between the energy capacity in fuel (gasoline) and the force needed to move an automobile. The automobile has tremendous mass and therefore needs a large force to move the mass. It will take a large amount of energy in the form of chemical energy (gasoline). Where does this force come from? The energy stored in the bonds in gasoline. Most of the students should already know that energy cannot be created nor destroyed, only converted from one form to another. (Law of Conservation of Energy) Where did the energy come from in the gasoline?
In Life Science/Biology, on the unit of energy, make the connection between photosynthesis and the capture of light energy from the sun by green plants. Use the conversion of that energy from radiant to chemical and the formation of sugar by the plants as a food source for animals. When animals consume sugar from the plants as food, where did the energy originally come from? Do all Animals need energy? What is the purpose of eating that food?
In Health, when dealing with Nutrition, consider the major groups of foods. Use the sugar group as the example. Ask the students to bring in a box of their favorite food. Read the label as to the calorie content of the food. They will be converting calories into work. Energy is stored as calories in the food we eat.
For the purpose of this laboratory investigation, the BMR (Basal Metabolic Rate) will be discounted. This is the amount of energy your body needs to carry out basic metabolism (breathing, heart beating, blood circulation, and all other metabolic cellular functions). This is a demonstration to assist the student understand the connection between food (fuel for animals) and human movement (work)
In this experiment you will be moving your weight, converted to mass a certain distance. You will need to convert your weight in Kilograms or pounds to mass. You will also need to measure out a specific distance. For this lab you might consider climbing a flight of stairs, or walking 1000 meters. Once you convert your weight to mass, then you need to convert your mass to a FORCE.
These are the science process skills needed to do this laboratory investigation.
Experimenting, Hypothesizing, Measurement, Observation, Prediction
Information needed to make the connections:
WORK = FORCE (X) DISTANCE
(W) WORK is the amount of FORCE needed to move an object a certain distance. Calculate the force in Newtons. (N) Work is done only when FORCE causes a change in the motion of an object.
JOULE = A Unit of WORK
(J) 1 N (x) m = 1 J (N = Newton)
1 Kg (x) m2/s2 = 1 J (Kg = Kilograms)
You will use the formula for Newtons (N) (X) distance in meters (m) equals JOULES (J). You will convert your mass to a FORCE in Newtons (N), then move the mass a certain distance in meters. The answer to the problem will be in JOULES of energy
ENERGY = The ability to do WORK
(E) Energy is measured in Joules
Law of Conservation of Energy = Energy cannot be created nor destroyed.
Energy is our potential to do some type of work. We use energy constantly.
GRAVITY = Force of attraction between the two bodies of matter due to their mass. The Earth exerts a force on you of 9.8 m/s2. This is a constant and always applies, except in space.
calorie = Amount of energy needed to raise 1 gram of water 1oC.
Calorie = A Kilocalorie or 1000 calories (referred to as Big "C" calorie)
You will determine how many calories you will burn to do work. The answer will be different for each person depending on the mass of the person and the amount of work being done.
Measure your weight in pounds (or) = ____________lbs.
Measure your weight in kilograms = ____________Kg
(A Kilogram is roughly 2.2 pounds)
Multiply your weight in pounds by 4.45N/lb* ____________N
Multiply your weight in kilograms by gravity 9.8m/s2 ____________N
*(This is a conversion factor, from HOLT Science Spectrum 2001)
Your weight is now a force exerted on the EARTH expressed as NEWTONS (N).
Measure a specific distance in meters, or centimeters. Use the rise of one stair and then multiply by the number of stairs to get the total distance that you will move your mass. This will take FORCE to move mass. Remember that the formula for WORK was force (x) distance: An example of force is an automobile that has great mass moving at a slow rate of 10 meters/hour. Compared to a bullet, which has small mass, moving at a great rate of speed like 1000 meters/sec.
WORK = FORCE (X) DISTANCE
You have your weight converted to FORCE and a specific distance. You can now calculate WORK which is measured in JOULES
_______N = your force in Newtons (x) distance moved _______m
1 Calorie = 4186 J
Divide WORK done in JOULES
Calories needed to do WORK
4.45 (X) 200 pounds = 890 Newtons
Move this mass 1000 meters
Newtons (X) meters = JOULES
890 Newtons (X) 1000 meters = 890,000 Newtons/meter or
Divide by the number of Calories to do WORK.
890,000 JOULES of FORCE
4186 Number of Joules in 1 Calorie
This will equal how many Calories were expended to do the work of moving your mass over a specific distance.
It took 212.6 Calories to move 1000 meters
Or, 21.26 Calories to move 100 meters
Or, 2.126 Calories to move 10 meters
What are some other examples you can think of?
How many calories to walk a mile?
How many calories to walk around the earth?
Remember that this is using Calories from food and that some of our food is in the form of complex sugar and some is stored as fat or oil. Read the labels on food packages. Most adults need between 2,000 and 3,000 Calories per day. Bring in a package of your favorite food and the label indicating Calories
1 cup skim milk = 86 calories
1 cup ice cream = 185 calories
1 apple = 81 calories
1 slice of white bread = 67 calories
What is your favorite food and how many Calories are in that food?
1. Be aware of the difficulty some student will have with the math involved, make sure you go step by step with the calculations.
2. Be sure to have covered the specific topic in order for the exercise to be relevant to the student.
CORE CURRICULAR CONTENT STANDARDS:
(These are New Jersey State Core Curricular Content Standards. New Jersey has adopted the National Standards in Science as the State Standards)
3.1.H Inquiry and Research (Language Arts)
3.5.A Constructing Meaning (Language Arts)
4.1.B Numerical Operations (Math)
4.2.D Units of Measurement (Math)
4.5.A Problem Solving (Math)
5.1.A Habits of Mind (Science Process)
5.5A Matter, Energy and Organization in Living Systems (Science Content, Life Science)
5.7.A Motion and Force (Science Content, Physical Science, Physics)
5.7.B Energy Transformations (Science Content, Physical Sciences, Physics)
American Association for the Advancement of Science.(2001) Atlas of Science Literacy: Project 2061. Washington, DC.
Dobson, Ken, Holman, John, and Roberts, Michael,. (2001) Science Spectrum: A Physical Approach Holt, Rinehart, Winston Austin, Texas
New Jersey Department of Education, (2002) New Jersey Science Curriculum Framework,
Rakow, S.J. (2000), NSTA Pathways to the Science Standards: Middle School Edition.
NSTA Press, Arlington VA.
Trowbridge, L.W., Bybee, R.W., and Powell, J.C.(2004). Teaching Secondary School Science: Strategies for Developing Scientific Literacy. Pearson/Merrill Prentice Hall, Upper Saddle River, New Jersey