Power
Power is the rate of doing work. Power = Work / Time. P = W/tThe 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.
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 FrictionCheck your answers here:
Solution to the Friction ExerciseExercise 2
Exercise on Perpendicular ForcesCheck your answers here:
Solution to the Perpendicular ForcesExercise 3
Exercise on Normal ForcesCheck your answers here:
Solution to the Normal ForcesExercise 4
Exercise on Vertical ForcesCheck your answers here:
Solution to the Vertical ForcesExercise 5
Exercise on Total ForcesCheck your answers here:
Solution to the Total Forces