Introduction to Power
Power
Power is the rate of doing work. Power = Work / Time. P = W/t
The unit of power is Watt (W) where 1 watt (W) = 1 J/s
Example:
A cord is used to sled a box across the ground without accelerating the sled.
The cord makes an angle to the horizontal.
Question:
Does the force applied through the cord do work on the sled?
- No, the force F does no work.
- Yes, the force F does work.
- Only part of the force F does work.
- You can't tell from this drawing.
Answer:
Only the part of the force that is parallel to the distance moved does work on the sled.
This is the horizontal part of the force F.
Exercise 1
Exercise on Friction
Check your answers here:
Solution to the Friction Exercise
Exercise 2
Exercise on Perpendicular Forces
Check your answers here:
Solution to the Perpendicular Forces
Exercise 3
Exercise on Normal Forces
Check your answers here:
Solution to the Normal Forces
Exercise 4
Exercise on Vertical Forces
Check your answers here:
Solution to the Vertical Forces
Exercise 5
Exercise on Total Forces
Check your answers here:
Solution to the Total Forces
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Date of last modification: 2022