Chapter 1 - Energy Flashcards
How is energy created?
Energy can neither be created nor destroyed It can only be changed from one form to another.
What is the unit for energy?
The unit for energy is the joule. One joule is a very small amount of energy, so we often use kilojoules (kJ) which is equal to 1000J. For a long time, a unit called a kilocalorie A.K.A a calorie, was used for the energy stored in food. 1 kilocalorie is equal to 4.2 kJ
What are some common energy stores?
Food and fuel store chemical energy, when a mother lifts her baby up- the energy is stored gravitationally,When springs are compressed when you sit on a bed; energy is stores elastically, all moving objects store kinetic energy.
What are some types of energy transfers?
In a torch or flashlight, electric current transfers energy from the battery to the bulb.
Energy can be transferred through the sun or a candle in the form of light. Energy is also transferred by heating
Musical instruments transfer energy to your ear as sound.
An electric current, light, sound, and forces cannot be stored. There are the ways in which energy is transferred.
Inside the sun a process called nuclear fusion is happening all the time; The sun is nuclear store of energy. Hydrogen atoms combine to form helium, and energy is released.
What do the symbols represent in energy transfer diagrams?
The circles show the transfer of energy and squares show the energy stores.
Describe energy transfers involving gravity, where the position changes.
If we take the example of a boy going on a cycle on a hill:
When he goes up the hill, the energy is transferred from a kinetic energy to a gravity store. When he goes downhill, the energy is transferred from a gravity store to a kinetic store.
When the boy pedals, energy stored chemically is transferred to energy stored kinetically.
What is energy dissipation?
Energy is transferred in processes that change something. In all processes , some energy is transferred to the surroundings, and heats up a bit. This usually happens because they are heated by friction or a sound is produced.
Eventually all the energy ends up in the surroundings and energy that is dissipated usually is transferred to the surroundings. Energy that is dissipated is no longer useful.
What is Gravitational Potential Energy?
GPE is the energy that an object has because of its position. The GPE Of an object depends on its mass and the gravitational field constant, and your distance from the centre of the Earth.
What is Kinetic Energy?
Kinetic Energy is the energy an object has when it is moving. The KE of an object depends on the mass and the speed of the object.
How is energy dissipated when things move up and down?
When objects move up and down, energy is dissipated by friction and air resistance.
How does a pendulum’s energy transform?
In a pendulum, when you pull back the pendulum and swing it, some energy is dissipated through air resistance/friction. When you pull the pendulum back you also lift it up so the GPE increases. When you drop the pendulum, the energy is transferred to a kinetic store.
What is elastic potential energy?
EPE is the energy that all objects that can stretch and be compressed and then deform have.
How does energy transform when a ball is bounced?
When a ball hits the ground, it deforms. Its kinetic energy is transferred to EPE when it changes shape. It changes back to its original shape and bounces back up. The EPE that has been stored is transferred to KE. When it reaches the top, all of its kinetic energy is transferred to GPE.
Will a ball reach its original height after being bounced?
A ball won’t reach its original height after being bounced as some energy was dissipated through the sound.
Name an example of elastic potential energy in the human body?
A tendon is a band of tissue that connects a muscle to a bone One example is the Achilles tendon in your calf. When you walk, this tendon stretches and stores energy and then releases it again. Some animals. such as kangaroos and frogs, can make huge leaps because of EPE storied in their tendons.
