Science - Energy | Test #10 Flashcards
(34 cards)
What is the First Law of Thermodynamics?
The first law of thermodynamics states that Energy can not be created or destroyed
Energy can only change forms such as potential energy to Kinetic energy
This law is also known as the Law of the Conservation of Energy
Heat Definition
Heat is the form of energy that is transferred between systems, objects, or areas with different temperatures
Heat will generally move from objects or areas that have higher temperatures to objects or areas that have lower temperatures
The transfer of heat will continue until equilibrium has been achieved where both objects or areas have the same temperature
Temp Definition
The term Temperature is the measure of the average energy of motion of the particles of a particular substance, which is affected by heat
E.g ice has a lower temperature than water because there is less heat affecting the water molecules compared to the water
Heat Transfers
There are 3 main forms of transferring heat between objects: Conduction, Convection, and Radiation
Conduction
the transfer of heat directly from one object to another
E.g stove heating up a pot of water
Convection
which has heat moving through a liquid or a gas
E.g warmer air rises, and cooler air falls
Radiation
heat being transferred by electromagnetic waves
E.g heat felt from a fire without having to touch it
Heat’s effect on substances
Most substances will have three main temperature points:
Freezing point(liquid to solid)
Boiling point(liquid to gas)
Ignition point(temperature which a substance will combust)
Example: Ethanol
Freezing point = -114 degrees
Boiling point = 78 degrees
Ignition point = 365 degrees
Some substances, such as water, does not have an ignition point because it cannot be further oxidized or burnt
Second Law of Thermodynamics
Law of Entropy
From an Energy Conversion standpoint, the Law of Entropy states that when energy is converted into another form of energy, not all the energy is converted into that new form of energy
Second Law of Thermodynamics Example
Example:
Turning on an incandescent light bulb
When electricity is converted within the light bulb create light energy, the majority of the energy is converted into heat energy in the process
Heat is usually the traditional “waste” of most energy transfers
Heat and Mechanical Motion
There are several mechanisms that humans have created that allow humans to utilize heat transfers in more constructive ways instead of being the byproduct of energy transfers
Heat Pump
Heat pumps allow for machines to make heat flow from one area to another area
Example:
The Compressor of a refrigerator forces coolants to circulate and remove heat from within the refrigerator and transfer that heat away from the refrigerator
Heat Engine
The heat engine is designed to convert heat energy into mechanical energy
Example: Steam engines
The boiler in steam engines allows for the heating of water, which will create an expansive gas that drive a piston to move
Why is it easier to move something on round wheels?
Round wheels provide a minimal amount of contact with the ground while maintaining a consistent level to the vehicle
The minimal amount of contact with the ground reduces the amount of friction with the ground, which allows a vehicle to not waste too much energy to move
Definition of Friction
Friction is the resistance that an object encounter when it is in contact with another object or substance
The greater the resistance, the greater the amount of friction
The byproduct of friction is heat, and most mechanical operations have to account for the increase of heat through friction
Ex. Space capsules returning to earth with heat shielding
Types of friction
static, sliding ,rolling and fluid friction
Static Friction
Static friction is the friction that occurs when an object stays at rest on another non-moving object or substance
Ex. furniture sitting on the ground
The friction with the ground prevents the furniture moving as the earth rotates
Sliding friction
Occurs when one object is moving against another object or substance
Ex. would be an object sliding on ice
The ice provides some level of friction, bit the amount of friction is reduced compared to rougher surfaces
Heat is created when the friction occurs, which melts the ices and provides a layer of water between the ice and the object and increases the slipperiness of ice
Rolling friction
Rolling friction occurs when an object is rolling across surface or another object
As an object is rolling across a surface, it will inevitably slow down unless force is applied to the object
Rolling friction is much weaker than static and sliding friction
Ex. moving bicycle
A bicycle can stay upright and self correct itself as long as there is a force pushing the bicycle
The force will allow the bicycle to act against the ground and keep it upright
Fluid friction
Fluid friction occurs when an object moves through a liquid or gas
All objects will experience a level of fluid friction as they move through the substance, and the level of viscosity will affect how much friction will occur
The greater viscosity, the greater the amount of fluid friction
Ex. swimming through oil
Even though oils are more slippery than water the viscosity and density of oil will make it harder swim through compared to water due to the increase fluid friction
In our universe, what emits the most radiation?
Stars are the main known source of radiation, but there are sources of powerful cosmic rays that have not been determined yet
Properties of Radiation
Radiation is a form of energy that moves through free space
It does not need particles in order to transmit or transfer its energy
Properties of Radiation Example
Example: Light is a form of Radiation
Stars, such as our Sun, produce various forms of Radiation
Transfer of energy from the sun to the earth
Energy that is produced on the sun can travel to earth in about 8.3 mins
The earth does require the radiation from the sun to help plants grow through photosynthesis, and produce heat on earth through absorption in matter
The earth’s magnetic field helps to deflect harmful radiation from the sun from damaging the earth
