Working In Natural Gas Student Resource

Working with natural gas frequently requires understanding and/or using physics. Here are some key terms and concepts.

Work

Work is done when a force that is applied to an object, moves that object.

  • Work is calculated by multiplying the force by the amount of movement of an object, (W = F * d) For example: A force of 10 newtons, that moves an object 3 meters, does 30 newton-meter (n-m) of work

figure 1

You Move, You Work Sitting and looking at a computer screen is not work. Tapping on the keyboard and making the keys move is work. Your fingers are applying a force and moving the keys. Driving to your job is not work because you just sit, but the energy
your car engine uses to move the car does work. You have to exert a force AND move something to qualify as doing work.

  • Work is measured in units of newton-meters
  • Work transfers energy from one object to another
  • Work is also linked to the expansion and compression of gas—think pipelines
    • When gas tries to expand, it exerts an increasing force on the surfaces of a container and can make those surfaces move; the gas is doing the work and transferring energy to the container
    • Measuring work done by gas is done at the initial and final states, and often while things are happening—in intermediate states The formula W = P (delta)V is used to figure out the total work done on, or by, a gas system; W stands for work,
      P is the pressure of the system (for gases), and delta V is the change in volume for the system A variation would be W = V(delta P), where V is volume, and delta P is the change in pressure; the delta values are taken at the beginning
      and end.

Power

Power is the rate at which work is accomplished over time.

  • Power is calculated by dividing work by time (P = W/t)
    • For example: Carrying a load up a flight of stairs requires the same amount of work whether the person carrying it walks or runs; however, more power is required to run because the work is completed in a shorter amount of time.
  • Power is measured in units of Joule or Watt
    • A Watt is one Joule per second; kilowatts (a thousand watts) is most commonly used
    • A joule is the same thing as a newton-meter

Energy

Energy is the ability to do work.

  • Energy is found in several different forms
    • Chemical energy (burning fuel), electrical energy, thermal energy (heat), light (radiant energy), mechanical energy, and nuclear energy
  • Energy makes everything happen; there are two types:
    • Stored energy is called potential energy
    • Moving energy is called kinetic energy

    Figure 3: Experience stored and moving energy

    Try this!

    Put a pencil at the edge of a desk and push it off to the floor. The moving pencil uses kinetic energy. Now, pick up the pencil and put it back on the desk. You used your own energy to lift and move the pencil. Moving it higher than the floor adds energy
    to the pencil. As it rests on the desk, the pencil has potential energy. The higher it is, the further it could fall. That means the pencil has more potential energy.

     

  • All forms of energy can be converted to other kinds of energy.
    • Isaac Newton’s Law of conservation of energy, says: Energy may be transformed from one form to another, but it cannot be created or destroyed
  • Energy is measured in different ways
    • Traditionally, in Btu, which stands for British thermal unit and was invented by the English, hence its name
    • Btu’s measure the amount of heat energy it takes to raise the temperature of one pound of water by one-degree Fahrenheit, at sea level
    • One Btu equals about the energy generated by one blue-tip kitchen match
    • One thousand Btu’s roughly equals: an average candy bar or 4/5 of a peanut butter and jelly sandwich
    • It takes about 2,000 Btu’s to make a pot of coffee
  • In the metric system, energy is measured by volume in units of Joules, pronounced just like the word jewels
    • A thousand joules is equal to a British thermal unit
      • 1,000 joules = 1 Btu, so it takes about 2 million joules to make a pot of coffee

  • There are also Kilojoules and Gigajoules (pronounced “gee-jay”), where “kilo” means 1,000 and “giga” means 1 billion
    • 1,000 joules = 1 kilojoule = 1 Btu
    • A piece of buttered toast contains about 315 kilojoules (315,000 joules) of energy; with that energy you could:
      • ✓ Walk briskly for 15 minutes, or jog for 6 minutes
      • ✓ Bicycle for 10 minutes
      • ✓ Sleep for 1-1/2 hours
      • ✓ Run a car for 7 seconds at 80 kilometers per hour
      • ✓ Light a 60-watt light bulb for 1-1/2 hours
      • ✓ Lift a sack of sugar from the floor to the counter 21,000 times!
      • ✓ An average single-family home in a city or town with 4 fairly distinct seasons (thinkPrince George or Fort St. John) uses about 160 gigajoules of natural gas energy per year
    • An average single-family home in a city or town with 4 fairly distinct seasons (think Prince George or Fort St. John) uses about 160 gigajoules of natural gas energy per year

Pressure

Pressure is the amount of force exerted per unit area (on a given surface).

  • Pressure is traditionally measured in PSI (pound per square inch)
  • In the metric system, we use Pascal which is one Newton over one metre; n/m.