Energy transfers Flashcards
What is the formula for kinetic energy?
0.5 x mass x speed^2
What is KE?
1/2 x M x v^2
What is the formula for gravitational potential energy?
m x g x h
What is the Law of Conservation of energy?
Energy can be stored or transferred between stores, and dissipated
+It can never be created or destroyed
+The total energy of a closed system has no net change
Kinetic energy
Any moving object will have this.
Chemical energy
anything that can release energy through a chemical reaction.
Gravitational potential
Any object that is is in the air.
Elastic potential
Anything stretched
Electrostatic
Two charges that attract or repel each other
Magnetic
Two magnets that attract or repel each other
Nuclear
atomic nuclei release energy from this store in nuclear reactions
What is the formula for efficiency?
Useful energy/total energy (j)
When is energy useful?
When it is transferred from one store to a useful store.
What is hydro-electricity?
+A renewable energy resource
+Involves flooding a valley by building a big dam
+Rainwater is caught and allowed out through turbines
What are solar cells?
+Solar cells are made from materials that use energy transferred by light to create an electric current.
+It is often used in remote places & powers electric road signs and satellites.
What are the advantages of solar cells?
+There’s no pollution.
+There are no running costs.
What are the disadvantages of solar cells?
+Initial costs are high (very expensive)
+Most suitable for sunny countries, but can be used in cloudy countries like Britain.
+You can’t make solar power at night
+You can’t increase production when there’s extra demand.
What are the advantages of hydro-electricity?
+No pollution
+An advantage is it can immediately respond to increased electricity demand - more water can be let through turbines to generate more electricity.
+Minimal running costs
+Generally a reliable energy source.
What are the disadvantages of hydro-electricity?
- There is a big impact on environment due to flooding of valley and (possible) loss of habitat for some species.
- Initial costs are high
