Conservation of Energy Flashcards
(28 cards)
When does an object have energy in its kinetic energy store?
When it is moving
When does an object have energy in its thermal energy store?
When it is hot. The hotter the object the more thermal energy it has.
When does an object have energy in its chemical energy store?
During a chemical reaction
When does an object have energy in its gravitational potential energy store? (GPE)
When it is a gravitational field.
When does an object have energy in its elastic potential energy store?
When it is stretched
When does an object have energy in its electrostatic energy store?
2 charges attracting or repelling
When does an object have energy in its magnetic energy store?
2 magnets attracting or repelling
When does an object have energy in its nuclear energy store?
Atomic nuclei releasing energy during nuclear reactions
What is the formula to calculate kinetic energy.
KE=0.5xmxv^2
Calculate the speed of an object if the KE= 5610J and it is 1500g.
86.4869932m/s
What is the formula to calculate GPE?
ΔGPE=mgΔh
Calculate the mass of an object on earth if change in GPE is 1780J and change in height is 45cm
395.555555556Kg
State the law of conservation of energy.
Energy can be stored, transferred between stores and dissipated- but it can never be created or destroyed. The total energy of a closed system has no net change
Name 4 ways energy can be transferred and give an example as well.
Mechanically- pushing, stretching, squashing
Electrically- charges moving round a circuit
By heating- heating a pan on a hob
By radiation- energy from the Sun reaching Earth by light.
When is energy useful?
Energy is only useful when it is transferred from one store to a useful store.
What is the formula for efficiency?
Efficency=(𝑢𝑠𝑒𝑓𝑢𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟𝑟𝑒𝑑𝑏𝑦 𝑑𝑒𝑣𝑖𝑐𝑒 (𝐽))/(𝑡𝑜𝑡𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑡𝑜 𝑑𝑒𝑣𝑖𝑐𝑒 (𝐽))
Calculate the efficiency of a fridge which uses 56kJ of energy and 12,005J is transferred into cooling the food.
21.4375%
What is a Sankey diagram used to show?
Energy transfer
What can be used to reduce energy transferred by friction?
A Lubricant like oil.
What reduces the rate of energy transfer by Heating?
Insulation
Name 5 renewable energy resources
Bio-fuels, Wind, Solar (the sun), Hydro-electricity, Tides
Give 2 advantages to Bio-fuels.
Carbon neutral
Reliable energy resource
Give 2 disadvantages to Bio-fuels.
Cost to refine bio-fuels is very high
Large areas of forest may have to be cleared to allow crops to grow.
Give 2 advantages to wind power.
No pollution produced
running costs are minimal
