Energy 1

Page 1

Introduction

Energy- The ability to move things or change things

Kinetic Energy- The energy of moving things

Gravitational Potential Energy-The energy stored in something when it is lifted up

Elastic Potential Energy-The energy stored when it is bent or stretched

Electrical Energy-The energy of electrical charges

Chemical Energy-Potential energy stored in the chemical bonds of material

Electromagnetic(light)Energy-Energy that travels in waves. (light)

Particles-the tiny bits of matter that make up a material or object

Thermal Energy-the total energy of the moving particles that make up an object

Temperature-The average energy of the moving particles that make up an object

Heat-Thermal Energy moving from one place to another

Specific Heat-A measurement that tells you how much energy is needed to raise the temperature of a material

Chemical Energy-Energy that is stored in the substance and released in a chemical reaction(burning wood, eating an apple)

Conductors- materials that allow electricity to flow through(mostly metal)

Insulator- materials that don't allow electricity to flow through

Potential energy- stored energy

Kinetic energy-energy in motion

Thermal energy- the vibration and movement within substances causing heat

Checkpoint 1

There are two forms of energy:

Potential

Kinetic

Potential energy is the energy an object has relative to the position of another object.

The kinetic energy of an object can easily be determined by an equation using the mass and velocity of that object.

Kinetic energy: (KE) is KE = 0.5 x mv2.

Here m stands for mass, the measure of how much matter is an object, and v stands for the velocity of the object or the rate at which the object changes its position

Your answer should always be stated in joules (J), which is the standard unit of measurement for kinetic energy.

If you are solving a problem where the mass isn’t given, you will have to determine the mass yourself.

This can be done by weighing the object on a balance and obtaining the mass in kilograms (kg).

Tare the balance. Before you weigh your object, you must set it to zero. Zeroing out the scale is called taring

Place your object in the balance. Gently, place the object on the balance and record its mass in kilograms.

If necessary, convert grams to kilograms. For the final calculation, the mass must be in kilograms.

Velocity is defined by the equation, displacement divided by time: V = d/t. Velocity is a vector quantity, meaning it has both a magnitude and a direction. Magnitude is the number value that quantifies the speed, while the direction is the direction in which the speed takes place during motion.

For example, an object’s velocity can be 80 m/s or -80 m/s depending on the direction of travel.

To calculate velocity, simply divide the distance the object traveled by the time it took to travel that distance. If you don't know the mass or velocity of the object, then you'll have to calculate it.

Determine the kinetic energy of a 55 kg woman running with a velocity of 3.87m/s. Since you know the mass and velocity of the woman, you can plug it into the equation. Once you've plugged in the mass and velocity, you can solve for kinetic energy (KE).

Square the velocity and then multiply all of the variables together.

Kinetic energy is energy possessed by a body by virtue of its movement.

Potential energy is the energy possessed by a body by virtue of its position or state.

The law of conservation of energy states that energy cannot be destroyed but can only be transformed from one form into another.

When a spring is stretched to one side, it exerts a force to the other side so it can come back to its original state.

The word "kinetic" is derived from the Greek word kinesis, which means "motion." The terms "kinetic energy" and "work", as understood and used today, originated in the 19th century.

Checkpoint 2

Potential energy due to the position of an object above Earth’s surface is called gravitational potential energy

Gravitational potential energy depends on an object’s weight and its height above the ground

Gravitational potential energy (GPE) = weight × height

Potential energy due to an object’s shape is called elastic potential energy

Potential energy is energy that is stored in a person or object.

Gravitational potential energy is due to the position of an object above Earth’s surface. The object has the potential to fall due to gravity. Gravitational potential energy depends on an object’s weight and its height above the ground (GPE = weight x height).

Elastic potential energy is due to an object’s shape. It results when an elastic object is stretched or compressed. The more it is stretched or compressed, the greater its elastic potential energy is.

Chemical energy and nuclear energy are other forms of potential energy.

Checkpoint 3

Anything that is moving has kinetic energy

The total kinetic energy of moving particles of matter is called thermal energy.

The thermal energy of matter depends on how fast its particles are moving on average, which is measured by temperature, and also on how many particles there are, which is measured by mass.

Temperature is the average kinetic energy of particles of matter.

A thermometer can measure temperature with a liquid that expands when it gets warmer and contracts when it gets cooler

The SI scale for measuring temperature is the Kelvin scale. Celsius and Fahrenheit temperature scales are also commonly used. You can use conversion factors to convert temperatures between the different scales.

Heat is the transfer of thermal energy between substances. Thermal energy is the kinetic energy of moving particles of matter, measured by their temperature.

Thermal energy always moves from warmer to cooler substances until both substances have the same temperature.

Specific heat is a measure of how much energy it takes to raise the temperature of a substance. It is the amount of energy (in joules) needed to raise the temperature of 1 gram of the substance by 1 °C

Specific heat is also how fast something heats up or cools down.

Specific heat is a property that is specific to a given type of matter, and substances vary in their specific heat. Metals tend to have low specific heat. Water has a very high specific heat.

Everything has its own specific heat

Every substance heats and cools at its own rate

Water has high specific heat

Lead has low specific heat

High specific heat- heats and cools slowly

High specific heat- highly reflective, transparent

Low specific heat-heats and cools quickly

Low specific heat- metal, lead is a good conductor

Checkpoint 4

Differences in kinetic energy explain why matter exists in different states

If particles do not have enough kinetic energy to overcome the force of attraction between them, matter exists as a solid

If particles have enough kinetic energy to partly overcome the force of attraction between them, matter exists as a liquid

If particles have enough kinetic energy to completely overcome the force of attraction between them, matter exists as a gas

According to the kinetic theory, particles of matter are in constant motion. The energy of motion is called kinetic energy.

The kinetic energy of particles of matter determines the state of matter. Particles of solids have the least kinetic energy and particles of gases have the most.

All three states of matter (solid, liquid and gas) expand when heated

When a solid is heated, its atoms vibrate faster about their fixed points

Liquids expand for the same reason, but because the bonds between separate molecules are usually less tight they expand more than solids

Molecules within gases are further apart and weakly attracted to each other

The specific latent heat of a substance is a measure of how much heat energy is needed to melt or boil it

Particles in both liquids and gases (collectively called fluids) move randomly

Brownian motion is named after the botanist Robert Brown, who first observed this in 1827

But in 1905, physicist Albert Einstein explained that the pollen grains were being moved by individual water molecules