Chapter 5

1. Chapter 5 Energy

2. Energy and Work • Energy – the ability to cause change. • Kinetic energy – energy in the form of motion. • Potential energy – stored energy. • Work – the transfer of energy through motion. • Work = Force x Distance • W = FD • Units = Joules (Newtons x meters)

3. Conservation of Energy • Mechanical energy – the total amount of kinetic and potential energy in a system. • Law of conservation of energy – states that energy can change form but it cannot be created or destroyed under ordinary conditions.

4. Human Energy • Calorie – a unit used by nutritionists to measure how much energy we get from specific foods. • 1 calorie ( = 1 kilocalorie) – 4180 Joules. • Each gram of fat supplies 9 calories of energy.

5. Temperature and Heat • Temperature – a measure of the average kinetic energy of the particles in a sample of matter. • Thermal energy – is the total energy of the particles in a material. • Heat – the thermal (or internal) energy that flows from something with a higher temperature to something with a lower temperature. (i.e. heat is energy transferred between objects at different temperatures.

6. Thermal Pollution • Thermal pollution – when waste heat significantly changes the temperature of the environment.

7. Measuring Thermal Energy • Specific heat – amount of energy it takes to raise the temperature of 1kg of a substance by 1o C. • Thermal Energy Equation • Q = mc∆T • Q is change in thermal energy • m is mass • c is specific heat • ∆ is the final temp. – the initial temp.