Energizing Motion: Work, Energy & Power
Work, energy, and power explore the concepts of work, different forms of energy like kinetic and potential, and power as the rate of energy transfer, providing insight into how energy drives physical processes. Work quantifies energy transfer through force and displacement, energy exists as kinetic (motion) or potential (stored), and power measures how quickly work is done, essential for understanding systems from swinging pendulums to running engines.
Overview of Work, Energy & Power
Work, energy, and power are defined by their key principles and relationships. Here’s the breakdown:
- Work: The transfer of energy when a force causes displacement, calculated as force times distance.
- Kinetic Energy: The energy of an object due to its motion, dependent on mass and velocity.
- Potential Energy: Stored energy based on an object’s position or state, like gravitational or elastic energy.
- Power: The rate at which work is done or energy is transferred, measured in watts.
Examples of Work, Energy & Power
Work Examples
- Pushing a 10 N box 5 m does 50 J of work (W = F × d).
- Lifting a 2 kg book 1 m against gravity (10 N) does 20 J of work.
- Pulling a sled with 30 N over 4 m performs 120 J of work.
Kinetic Energy Examples
- A 2 kg ball moving at 5 m/s has 25 J of kinetic energy (KE = ½mv²).
- A 1000 kg car at 20 m/s has 200,000 J of kinetic energy.
- A 0.5 kg bird flying at 10 m/s has 25 J of kinetic energy.
Potential Energy Examples
- A 2 kg book 3 m above ground has 60 J of gravitational potential energy (PE = mgh, g = 10 m/s²).
- A 1 kg rock at 5 m height has 50 J of potential energy.
- A stretched spring with k = 200 N/m and x = 0.1 m has 1 J of elastic potential energy (PE = ½kx²).
Power Examples
- Lifting 50 J of work in 5 s generates 10 W of power (P = W/t).
- A motor doing 200 J of work in 4 s produces 50 W of power.
- Running up stairs with 300 J of work in 3 s yields 100 W of power.