P7 Flashcards
What is the law of conservation of energy?
Energy cannot be created or destroyed, only transferred from one form to another.
Give the 9 different stores of energy.
Kinetic.
Heat/Thermal.
Light.
Gravitational Potential.
Chemical Potential.
Elastic Potential.
Electrostatic.
Nuclear.
Magnetic.
Energy from fuels can be used to __________.
propel objects/move them.
Give an example of stored energy and explain how it is used.
Elastic potential - used for changing the shape of objects, i.e. stretching and compressing them.
Give the steps to analysing a situation using energy.
- Choose two points in a process.
- Indentify which stores have more or less energy at these points.
- Work out the type of transfer that has transferred energy between the stores.
Give four ways in which energy is transferred.
Mechanically. Electrically. Heating by particles. Heating by radiation.
Give the formula for working out KINETIC ENERGY.
K.E. = mass x 0.5 x velocity’2
Give the formula for working out how much energy has been transferred in a kilowatt-hour appliance.
Energy transferred = power (kW) x time (h)
What does the cost of an electrical device depend on?
How much electrical energy the device uses and the electricity tariff (cost per unit of electrical energy used.)
Give the formula for working out the cost of an electrical appliance.
Cost = number of kWh x cost per kW
What is the formula for work done?
Work done = force x distance
What is the formula for gravitational potential energy?
gravitational potential energy = height x mass x gravitational field strength
What does the rate of which energy is transferred through walls of your house depend on?
The thickness of the walls and what they are made of and the difference in temperature between the two sides of the walls.
The rate of temperature drop is greater if the walls are ________.
thinner.
