Laboratory 1
Introduction to Conservation of Mechanical Energy
Main Topics:
Energy, Conservation, Kinetic energy, Potential energy, Friction
Learning Goal:
Explain the Conservation of Mechanical Energy concept using kinetic and gravitational potential energy
Part 1: Definition Builder
For all of the definitions provide verbal descriptions as well as formulas if possible. Please, discuss your definitions with a neighbor.
- What is Energy?
Energy is the ability to do work. There are many different types of energy: heat
energy, kinetic energy, potential energy, light energy, electrical energy, and many
others. Mechanical energy is measured in joules, which is Newton’s/meter.
2. What is Power?
Power is the time rate at which work is done or energy is transferred or used. Power is measured in
watts or joules/second. Power = work divided time
3. What is Potential Energy? Please, provide an example.
Potential Energy is energy that is waiting to be converted into power. Potential Energy is the energy
that is stored in an object and has to potential to be converted into another type of energy to perform
work. The formula for Potential Energy is PE = m x g x h. (Mass x Acceleration due to Gravity x Height).
An example would be if a person standing flat on the ground held a tennis ball up in the air and were
about to drop it. By holding the tennis ball up in the air, the ball has the potential to be dropped and
fall to the ground converting the energy from potential to kinetic, which is energy of motion.
4. What is Kinetic Energy? Please, provide an example.
Kinetic Energy is energy in motion. Any moving object has Kinetic Energy. The formula for kinetic
energy is Ek = ½ mv2. An example of Kinetic Energy is from the example above with the person holding
the ball. As soon as that ball is dropped from standing height to the ground the ball had Kinetic Energy
since it was falling (moving) towards the ground.
5. State the Law of Conservation of Energy.
The Law of Conservation of Energy states that energy cannot be created or destroyed, but can change
its form.
Part 2: Application of Concepts
|
Problem 1 |
Problem 2 |
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| What can you say about the skater’s potential energy relative to the reference level at ground? | At the top bullet skater has 100% potential energy. Potential Energy is the energy that is stored in an object and has to potential to be converted into another type of energy to perform work. Since the start position is higher off of the ground then the starting position of Problem 2 the Potential Energy is higher. | The skater here at this point also has potential energy but not as much as in Problem 1 because the potential to fall a further distance to the ground is smaller. |
| What can you say about the skater’s kinetic energy? | Since the starting point for the skater, where the potential energy became kinetic energy, was higher, the kinetic energy increases because the velocity is higher. | On this problem, the kinetic energy decreases because the point where the potential energy turns to kinetic energy is closer to the ground so the velocity is smaller because the skater has a smaller distance to travel to the ground. |
| What is the value of total energy of the system? | The total energy of this system is 2856.68 Joules | The total energy of this system is 3023.53 Joules |
1. When the skater begins at the top of the track the skater’s potential energy is at its highest level because as the skater moves down the track and his kinetic energy increases, the potential for the potential energy to become kinetic becomes less and less therefore the potential energy level decreases towards the bottom of the graph. As the skater moves upwards, on the second half of the curve his kinetic energy decreases and his potential energy increases as he reaches the top of the other side of the curve because as he reaches the top the potential for him to come back down is at its highest once again.
2. When the skater begins at the top of the track, the skater’s potential energy is at its highest level and the level of kinetic energy is at its lowest. As the skater moves down the track his kinetic energy increases and reaches its maximum as the skater reaches the middle of the track and his velocity is at its highest value. As the skater rises up toward the other end of the curve, his kinetic energy is back at its lowest point because the skater is not longer in motion but in the air with the potential to skate back down the curve.
3. The total energy for this scenario is at approximately 4500 because the net energy or total energy is the sum of the highest potential energy and the lowest kinetic energy. The highest point of potiential energy is approximaty 4500 and the lowest kinetic energy is 0 and 4500-0=4500. The horizontal line would be across the graph at 4500.