Physics Topic 1: Energy

21 flashcards · Physics · by Marli Williams

1. System

   An object / group of objects

2. What happens when a System Changes?

   The way energy is stored also changes

3. Energy Stores

   Kinetic Elastic Gravitational Potential Electrostatic Magnetic Chemical Nuclear Thermal

4. How is energy transferred between stores?

   Via different Pathways Mechanical (Doing work) Electrical (Doing work in a electrical circuit) Heating (Transfer of heat) Radiation

5. Kinetic Energy & Equation

   Energy of Movement Ek = ½ x mass x (speed)2

6. Gravitational Potential Energy & Equation

   Energy of an object due to its height in a gravitational field Eg = mass x field strength x height

7. Elastic Potential Energy

   Energy stored in a elastic object when it is compressed or stretched Ee = ½ x spring constant x (extension)2

8. Specific Heat Capacity

   The amount of energy required to raise the temperature of 1kg of the substance by 1°C Change in Thermal Energy = Specific Heat Capacity x mass x temperature change

9. Required Practical - Investing Specific Heat Capacity

   Method: Start by assembling the apparatus Measure the initial temperature of the 1kg of metal block from the thermometer Turn on the power supply and start the stopwatch Whilst the power supply is on, the heater will heat up the block. Take several periodic measurements, eg. every 1 minute of the voltage and current from the voltmeter and ammeter respectively, calculating an average for each at the end of the experiment up to 10 minutes Switch off the power supply, stop the stopwatch and leave…

10. Required Practical - Investing Specific Heat Capacity: Variables

    Independent Variable - Time heated Dependent Variable - Temperature Control Variable: Material of the Block Potential difference supplied Current supplied

11. Parallax Error

    Not reading measurements at eye level

12. Zero Error

    Faulty equipment that doesn’t reset to zero properly. Example: The scale shows 5g when nothing is on the scale

13. Random Error

    Random errors are present when any measurement is made, and cannot be corrected.

14. Power

    The rate at which energy is transferred / work is done. Power = Energy transferred or Work done / Time

15. Conservation of Energy

    Energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.

16. Wasted Energy

    Energy that is not useful for the intended purpose it was transferred. Examples: Heat Light Sound

17. How to reduce wasted energy?

    Lubrication - Reduces Friction Insulation - Reduces energy from dissipating to the surroundings

18. Conduction

    Energy transfer via vibrating of particles Direction of energy transfer is from Hot to Cold

19. Conduction & Thermal Conductivity Relationship

    The higher the thermal conductivity of a material, the higher the rate of energy transfer by conduction across the material

20. Insulators

    Have poor thermal conductivity to reduce energy transfers

21. What is the strength of insulators based on?

    Temperature difference Thermal conductivity Thickness of material