P1. Conservation and Dissipation of Energy Flashcards
(37 cards)
What are chemical energy stores?
Chemical energy stores include fuels, foods, or the chemicals found in batteries. The energy is transferred during chemical reactions
What are kinetic energy stores?
Stores that describe the energy an object has because it is moving
What are gravitational potential energy stores?
Stores that are used to describe the energy stored in an object because of its position, such as an object above the ground
What are elastic potential energy stores?
Stores that are used to describe the energy stored in a springy object when you stretch or squash it.
What are thermal energy stores?
Stores that describe the energy a substance has because of its temperature
What factors affect the amount of energy in the kinetic energy stores?
Mass and speed
What factors affect the amount of energy in the gravitational potential energy stores
Mass and height
What factors affect the amount of energy in the elastic potential energy stores
Spring constant, displacement, mass and material
What factors affect the amount of energy in the chemical energy stores
Object’s mass, chemical composition, the type of bonds that are present
What factors affect the amount of energy in the thermal energy stores
The mass of the object, the specific heat of the object and the change in temperature of the objeft
What is the principle of conservation of energy?
Energy cannot be created or destroyed
Why do forces cause heating effects?
As energy cannot be created or destroyed, the energy taken from the motion of the objects is converted in heat
What are closed systems?
A closed energy system is unable to exchange energy and matter with their surroundings
What are some examples of energy stores and systems?
Collision - A moving object will start off with kinetic energy. Once it hits an obstacle, the kinetic energy can be transferred to the surroundings as thermal energy and sound waves. Some of the kinetic energy can be transferred to the obstacle causing it to move
Flying - If a ball is projected upwards it will initially have kinetic energy. As the ball rises higher into the air, the kinetic energy will be transferred into gravitational potential energy. Once the ball reaches its highest point, the gravitational potential energy will all be converted into kinetic energy as the ball back into the ground
What is work?
Work is done on an object when a force makes the object move
Energy transferred = work done
What affects the work done by a force?
The size of the force and the distance moved
How do you calculate work done?
Work done (Joules) = Force applied (Newtons) × Distance moved along the line of action of the force s (metres)
Why do objects become heated by frictional forces
The presence of frictional forces means that some of the energy input is transferred into thermal energy. Seeing as more work is done due to frictional force anyway, there is a greater amount of energy transfer.
What does the work done depend on when an object moves up or down?
How far it is moved vertically
Its weight
How do you calculate the change in an object’s gravitational potential energy store?
change in an object’s gravitational potential energy store = weight × change of height
How do you calculate the change of gravitational potential energy store?
change of gravitational potential energy store Ep = mass, m × gravitational field strength, g × height, h
How do you calculate kinetic energy?
Kinetic energy, Ek = ½ x mass, m × speed², v²
How do you calculate elastic potential energy?
Elastic potential energy, Ee = ½ × spring constant, k × extension², e²
