Work and Power
Class 9 Science: work and energy (work and power)
Carry a box up the stairs or along a flat floor, walking or running. Work out the work done and the power, and find when the work is zero.
Words to know
- Work
- Force × distance moved in the direction of the force. Unit: joule (J).
- Joule
- The work done when a force of 1 N moves something 1 m.
- Power
- Work done per second: power = work ÷ time.
- Watt
- Unit of power: 1 W = 1 J per second.
- Potential energy
- Energy stored because of height: m × g × h.
Quick check
Answer 3 questions to check what you learned.
Try at home
Time yourself walking up a flight of stairs, then running up. Your weight and the height are the same. Which time used more power?