Plain-English Meaning
Two people can carry the same box upstairs, but the one who does it faster has greater power output. Power P = W/t — work divided by time. The unit is the watt (W): 1 W = 1 joule per second.
Mechanics questions usually become easier once you identify whether the problem is about force balance, kinematics, energy, or conservation.
Deeper Explanation
For instantaneous power: P = dW/dt = F · v (force dot velocity). Average power = total work / total time. P (watts) = V × I (electrical), P = τω (rotational). Efficiency = useful power output / total power input.
Worked Example
Problem: A motor lifts a 200 kg load 10 m in 5 seconds. What is its power output?
- Work done: W = mgh = 200 × 9.8 × 10 = 19,600 J
- Time: t = 5 s
- Power: P = W/t = 19600/5 = 3920 W
Result: P = 3920 W = 3.92 kW
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At A Glance
Category: Mechanics
Levels covered: High School, College, Masters, PhD
Best use: Start with the formula meaning, then move to the worked example and quiz so the equation turns into a tool instead of a memorised line.