1. Efficiency

2. When you lift an object the chemical energy from your muscles goes to the object as gravitation potential energy, how much depends on the weight of the object and how high you lift it. Weight is measured in newtons (N). 1kilogram = 9.8N (kg*m/s²). Energy is measured in joules (J). The energy needed to lift 1N 1 metre high = 1 joule.

3. Energy supplied = useful energy + wasted energy.

4. Efficiency = useful energy OUT *100 total energy put IN
The efficiency of a process describes how well energy or power is converted from one form into another.
IT IS HOW WELL ENERGY IS CONVERTED FROM ONE FORM TO ANOTHER
Efficiency = useful energy OUT *100
total energy put IN
Efficiency is measured as a PERCENT

5. For example, an electric motor is used to lift an object
For example, an electric motor is used to lift an object. The object has 60J of gravitational potential energy when the motor is given 200J of electrical energy. Efficiency = 60J (useful energy out) 200J (total energy in) = .3 * 100 = 30% efficient

6. A light bulb transfers 15J of light energy for every 100J of electrical energy what is its efficiency?
15%
A washing machine uses 300J of electrical energy but only 100J is useful energy, what is its efficiency?
33%
A television produces 20J of light and sound energy together but is supplied with 80J of electricity how efficient is it?
25%

7. How high a mountain could you climb with the energy in just one Snickers candy bar? 
1 food Calorie = 4,187 J 1 Snickers = 250 Cal 1,569.6m or about 1mile

8. How much energy is stored in 1 pint of ice cream?
1 food Calorie = 4,187J
1 pint = 960 food Calories
4,002,000J

9. The energy efficiency is of the human in this figure is about 8%!
Energy Flow and Systems
The (output) work done against gravity when climbing a mountain.
The energy efficiency is of the human in this figure is about 8%!