Physics: Work, Energy, and Power

• Physics guide for the 2nd period covering work, energy, and power

Definitions

• Power is the rate at which work is done or energy is transferred, measuring how quickly energy is used or produced.
• Energy is the capacity to do work or produce change, a fundamental property of matter that can only be transformed.
• Work is done when a force acts on an object and causes displacement.
• Joule is the unit for work and energy and equals the amount of energy transferred when a force of one newton (N) moves an object one meter (m).
• Watt is the unit of power, defined as the rate at which work is done or energy is transferred.
• 746 watts equals one horsepower (HP).

Renewable Energy Examples

• Hydroelectric
• Wind
• Biomass
• Solar
• Geothermal

Non-Renewable Energy Examples

• Coal
• Natural gas
• Oil

Energy Definitions

• Geothermal energy is heat energy from the Earth's core.
• Biomass energy is energy from burning organic materials like plants, animal waste, and wood.
• Wind energy is generated by converting the kinetic energy of moving air into mechanical power using turbines.
• Coal is a fossil fuel from the remains of plants that lived millions of years ago, extracted and burned for electricity or heat.
• Natural gas is a hydrocarbon gas mixture, primarily methane, from dead organisms buried deep underground for millions of years.
• Solar Energy is derived from the Sun's radiation.
• Oil is a liquid fossil fuel from ancient marine organisms that is refined into gasoline and other products.
• Hydroelectric energy is derived from moving water.

Work Formula

• Variables used to calculate work include:
  • W = Work (Joules)
  • F = Force (Newtons)
  • D = Distance (meters)
  • t = time (s)

Work = Force x Distance x cos(θ) - W = F x D x cos(θ) Force = Work / (Distance x cos(θ)) - F = W / (D x cos(θ)) Distance = Work / (Force x cos(θ)) - D = W / (F x cos(θ))

Power Formula

• Power = Work / Time
  • P = W / t

Example Problems

• Pulling a wagon with 80 N of force at a 25° angle over 15m results in 1,087.57 Joules of work.
• If Link pulls the Master Sword with 600 N at a 45° angle and does 880 J of work, the sword moves 2.07 meters.
• Master Chief pushing a Warthog with 1200 N at a 30° angle over 10 meters does 10,392 Joules of work.
• Dragging a box of petunias 6m with a rope at a 35° angle, with 220 J of work, requires a force of 44.76 N.
• Pulling an ostrich 8m at a 15° angle with 650 J of work requires a force of 84.12 N.
• An elevator raising a 500 kg load 10 meters with 5000 N force and 2500 watts power takes 20 seconds.
• A car engine applying 1500 N over 200 meters in 10 seconds exerts 30,000 W of power.
• Kylian Mbappe sprinting 100 meters with 250 N force and 1500 watts power takes 16.67 seconds.