Forms of Energy
This is the energy an object has because it is moving.
What is kinetic energy?
This law states that energy cannot be created or destroyed.
What is the law of conservation of energy?
This diagram shows energy input, useful output and wasted output.
What is a Sankey diagram?
This term describes how well a system converts input energy into useful output energy.
What is efficiency?
What type of energy does an object have because it is moving?
What is kinetic energy?
This type of energy is stored in food, fuel and batteries.
What is chemical energy?
When a toaster is used, electrical energy is mostly transformed into this useful form of energy.
What is thermal energy?
In a Sankey diagram, the arrow that continues forward usually represents this output.
What is useful energy output?
This is the energy output that is not useful to the purpose of the system.
What is wasted energy?
Calculate the GPE of a 4 kg backpack sitting on a shelf 2 m high.
What is 80 J?
GPE = mgh = 4 × 10 × 2 = 80 J
This type of energy is stored when an object is lifted above the ground.
What is gravitational potential energy?
If a system has 100 J of energy input, the total useful and wasted output energy should add up to this amount.
What is 100 J?
In a Sankey diagram, a thicker arrow shows this.
What is a larger amount of energy?
A lamp has 100 J of input energy and 25 J of useful light energy. This is its efficiency.
What is 25%?
A 2 kg ball is moving at 5 m/s. Calculate its kinetic energy.
What is 25 J?
KE = ½mv² = ½ × 2 × 5² = 25 J
This type of energy is stored in stretched or compressed objects such as springs or rubber bands.
What is elastic potential energy?
This explains why the output energy of a system is equal to the input energy, even if some energy is wasted.
What is energy conservation?
A system has 200 J input energy and 120 J useful output energy. This is the wasted output energy.
What is 80 J?
A system with less wasted energy and more useful output energy is described as this.
What is more efficient?
As a roller coaster travels from the top of a hill to the bottom, what energy transformation occurs?
What is gravitational potential energy changes into kinetic energy?
Name two forms of energy that are often wasted by machines or appliances.
What are thermal energy and sound energy?
Explain why energy is not “lost” when a machine becomes hot and noisy.
What is energy being transferred or transformed into wasted thermal and sound energy?
A Sankey diagram shows 300 J input, 180 J useful output and 120 J wasted output. This is the efficiency.
What is 60%?
Compare two systems and explain which is more efficient using useful output and wasted output.
What is the system with the higher percentage of useful output energy?
A 3 kg object has 150 J of GPE. How high is it?
What is 5 m?
150 = 3 × 10 × h