What Kinds of Energy Are There?

Describe that energy can be considered to be either kinetic or potential; that energy can change form or be redistributed but the total quantity of energy is conserved


Calculating Kinetic Energy
Kinetic energy is the measurement of the motion of an object. In the above formula, m stands for mass (in kg) and v stands for velocity (in meters per second). Kinetic energy is measured in joules (J).
  1. What is the kinetic energy of a person who has a mass of 70 kg walking at 1 m/s?
  2. What is the kinetic energy of a train that has a mass of 100,000 kg traveling at 100 m/s?
  3. What is the mass of a car that is traveling with 98,000 J of kinetic energy at 7 m/s?
  4. Calculate the kinetic energy of a pendulum if it moves at an average of 1 m/s and weighs 100 g (there are 1000 g in 1 kg).
  5. Which has more kinetic energy: A 30 kg pit bull running at 2 m/s or a 5 kg Yorkie running at 5 m/s? Show your calculation.
  6. Which of the two dogs from #5 has more momentum (momentum = mass x velocity)? Show your calculation.
  7. Considering your answers to #5 and #6:
    1. Which dog will have more trouble stopping completely?
    2. Which dog will consume more calories if they both run for 5 minutes?
    3. Is it better for football players who need to break tackles to weigh more or to run faster? Why?
    4. Is it better for marathon runners to weigh less or run faster in order to conserve energy? Why?
Kinetic vs. Potential Energy
  1. Define potential energy and kinetic energy.
  2. For each of the following situations, describe how you would obtain the greatest amount of potential energy and where you could measure the greatest amount of kinetic energy:
    1. A ball suspended on a rod with a string (a pendulum)
    2. A ball and an inclined plane at 45 degrees
    3. A penny, cup and index card
    4. A long spring
    5. A two-meter high platform and a ball
  3. Potential energy due to gravity can be calculated by the following formula:

    How are height, mass and potential energy related? Answer in terms of what happens when height and mass increase.

Household Kinetic and Potential Energy

Find three examples of potential energy that is converted into kinetic energy. Potential energy is stored in fuel, things that can fall easily, anything that has a spring inside it, and anything that is capable of movement. Ask around your house or ask friends. For each example:

  1. Identify the example
  2. Describe the moment when it has the highest amount of potential energy
  3. Describe the moment when it has the highest amount of kinetic energy.
  4. Describe a moment when it has about the same amount of potential and kinetic energy (when it is moving, but has the potential to move twice as much as it’s currently moving).

Endothermic vs. Exothermic
  1. Define:
    1. Conservation of Energy
    2. Entropy
    3. Endothermic
    4. Exothermic
  2. How are conservation of energy and entropy related?
  3. How are endothermic and exothermic related?
  4. Answer the following for each station in #5:
    1. What is it?
    2. Make two observations about the station
    3. Is it endothermic or exothermic? Why?
    4. According to conservation of energy, no energy is gained or lost. Where is it going?
  5. These are the stations:
    1. hot pack
    2. cold pack
    3. water & ice
    4. lit candle
    5. rubbing alcohol (to put on your skin),
    6. rub your hands together for 30 seconds.
Household Reactions
  1. Around your house, find three chemical or physical reactions that happen on a regular basis. For each one, state:
    1. What is the reaction? Explain!
    2. Is it endothermic or exothermic? Why?
  2. Assume that your house is one big reaction – this is called a system. To an outside observer, is your house endothermic or exothermic? Explain your answer, including at least three things that are going on inside the house!
Water Lab
  1. Define the following:
    1. Thermal energy
    2. Temperature
    3. Thermometer
  2. Which cools faster: warm water or cold water? To answer this question you will do the following experiment. Start by getting 1 cup of cold water, 1 cup of warm water, ½ cup of cold water, ½ cup of warm water, 8 ice cubes and 4 thermometers.
  3. You will be measuring the temperature of the water to begin with, then cooling the water down with ice until the ice melts. What is your hypothesis?
  4. What is the independent variable?
  5. What is the dependent variable?
  6. Place the thermometers in each cup.
  7. Record the temperature every minute for three minutes.
  8. After three minutes, put two cubes of ice in each cup.
  9. Continue recording the temperature every minute until the temperatures are about the same three times in a row.
  10. Present your results in a table. Make a line graph from this table.
  11. Why did you get the results that you did? Explain using the terms from #1.
  12. Was your hypothesis supported? Why or why not?
  13. How could your hypothesis be modified to find out even more information.
Heat
  1. Define:
    1. Heat
    2. Temperature
    3. Thermometer
  2. Complete:

Fahrenheit – F Celsius – C Description
Water freezes
100
98.6
72 Room temperature
Temperature at the top of the room
Temperature at eye level in the room
Temperature of room temperature water