# Power and Efficiency

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##### Examples

###### Lessons

**Power and efficiency of accelerating a car**

A 1210 kg sports car can reach 100 km/h in 2.70 s.

- Find the power output of the engine.
- If the fuel used in this time produces a total of 718 kJ of energy, what is the efficiency of the engine?

**Power of pulling an object up a ramp**

An 87.0 kg cart is pulled up a ramp at a constant speed by an electric motor. The motor outputs 375 W and the ramp's incline 25.0°. What is the speed of the cart? Assume friction is negligible.