HEAT, LIGHT and SOUND UNIT
what we will cover:
- energy
- conduction, convection and radiation
- how heat travels
- frequencies
- speed of light, sound and heat waves
- reflection and mirrors
what we will cover:
- energy
- conduction, convection and radiation
- how heat travels
- frequencies
- speed of light, sound and heat waves
- reflection and mirrors
7D at work
here all the year 7D students are working hard completing their boiling water prac!!
7E heat role play
year 7E students as particles show what happens when heat energy is increased
Convection
watch the boys role play demonstrating convection
Radiation
here the boys demonstrate radiation
Energy
Energy is defined as the ability to do work. If you can measure how much work an object does, or how much heat is exchanged, you can determine the amount of energy that is in a system. As with work, energy is also measured in Joules. Energy is not created nor destroyed according to the Law of Conservation of Energy. Energy only changes form. It is transformed from one kind of energy to another. In fact, the energy that makes your body work can be traced back to the sun. Solar energy is transformed to chemical energy in the plants. We get chemical energy from the plants and animals we eat.
Transformation of Energy
If you wind up the rubber band in a model plane, you transform chemical energy into mechanical, heat and electrical energy. As you turn the propeller, potential energy is stored in the rubber motor of your plane. When you let the plane go, the spinning propeller has rotational kinetic energy. The moving plane and the air being pushed back both have kinetic energy. As the plane gains altitude, kinetic energy is transformed to potential energy. As the plane descends, potential energy is transformed to kinetic energy. Energy leaves the system as heat from friction. In addition, some energy leaves the system as sound energy.
Energy is defined as the ability to do work. If you can measure how much work an object does, or how much heat is exchanged, you can determine the amount of energy that is in a system. As with work, energy is also measured in Joules. Energy is not created nor destroyed according to the Law of Conservation of Energy. Energy only changes form. It is transformed from one kind of energy to another. In fact, the energy that makes your body work can be traced back to the sun. Solar energy is transformed to chemical energy in the plants. We get chemical energy from the plants and animals we eat.
Transformation of Energy
If you wind up the rubber band in a model plane, you transform chemical energy into mechanical, heat and electrical energy. As you turn the propeller, potential energy is stored in the rubber motor of your plane. When you let the plane go, the spinning propeller has rotational kinetic energy. The moving plane and the air being pushed back both have kinetic energy. As the plane gains altitude, kinetic energy is transformed to potential energy. As the plane descends, potential energy is transformed to kinetic energy. Energy leaves the system as heat from friction. In addition, some energy leaves the system as sound energy.
Energy can be classified as either stored (potential) energy and working (kinetic) energy. All energy can be measured in “Joules”.
Potential Energy = the energy that an object has as the result of its position or state. Some examples of potential energy include: chemical, elastic, gravitational, magnetic…
Kinetic Energy = the energy that appears in the form of an object’s motion. KE = 1/2mv2. Some examples of kinetic energy include: sound, electrical, light…
Mechanical Energy = kinetic and potential energy (of lifting, bending, stretching or twisting)
For instance, it is possible to calculate the potential energy of an apple that is 2 meters above the head of a businessman. The equation is: Gravitational Potential Energy = mgh. Mass = m. The acceleration due to gravity = 9.8m/s2 and h is the distance above the man’s head.
Thermal Energy = the total energy of the particles that make up a mass. Thermal energy is internal.
Heat = is a transfer of energy from one part of a substance to another, or from one object to another, because of a difference in temperature. Heat is a form of energy associated with the motion of atoms or molecules and is capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation. Heat is not contained in a mass; an object contains thermal energy.
Light Energy = Sometimes called radiant energy and is visible to the human eye. It is emitted by moving charged particles. Light sometimes behaves like particles, called photons, and at other times like waves.
Chemical Energy = The potential energy held in the covalent bonds between atoms in a molecule. Food is essentially stored potential energy.
Nuclear Energy = energy that is released when the nuclei of atoms are split (fission) or fused together (fusion).
Electrical Energy = energy that runs our appliances etc…
Convectionis the transfer of heat by the actual movement of the warmed
matter. Heat leaves the coffee cup as the currents of steam and air rise.
Convection is the transfer of heat energy in a gas or liquid by movement
of currents. (It can also happen is some solids, like sand.) The heat moves
with the fluid. Consider this: convection is responsible for making macaroni
rise and fall in a pot of heated water. The warmer portions of the water are
less dense and therefore, they rise. Meanwhile, the cooler portions of the
water fall because they are denser.
Conduction is the transfer of energy through
matter from particle to particle. It is the transfer
and distribution of heat energy from atom to
atom within a substance. For example, a
spoon in a cup of hot soup becomes warmer
because the heat from the soup is conducted
along the spoon. Conduction is most effective
in solids-but it can happen in fluids. Fun fact:
Have you ever noticed that metals tend to feel
cold? Believe it or not, they are not colder!
They only feel colder because they conduct
heat away from your hand. You perceive the
heat that is leaving your hand as cold.
Radiation: Electromagnetic waves that directly
transport ENERGY through space. Sunlight is
a form of radiation that is radiated through
space to our planet without the aid of fluids or
solids. The energy travels through nothingness!
Just think of it! The sun transfers heat through
93 million miles of space. Because there are
no solids (like a huge spoon) touching the sun
and our planet, conduction is not responsible
for bringing heat to Earth. Since there are no
fluids (like air and water) in space, convection
is not responsible for transferring the heat.
Thus, radiation brings heat to our planet.
How a radiometer works: You need to focus on the
edges of the vanes to explain the behavior of the
radiometer. Heat excites the black surface of the
vanes more than it heats the white surface. Black is
a good absorber and a good radiator. Think of black
as a large doorway that allows heat to pass through
easily. In contrast, white is a poor absorber and a
poor radiator of energy. White is like a small doorway
and will not allow heat to pass easily.
The difference in temperature between the warm, black side and the cooler white side causes gasses to creep along the surface of the vanes. This effect is known as "thermal creep." The faster gasses from the black side strike the edges of the vane at an angle with more force than the molecules from the cold side. The equal and opposite forces cause the radiometer to spin.
Why a radiometer runs backwards after the light is turned off. Heat escapes quickly from the black sides of the vanes. Thus, the black molecules cool off first. Meanwhile, the white molecules take longer to lose heat cool down. The result is that gasses from the white vane push off with more force (Newton's third law) and the vanes spin in the opposite direction.
matter. Heat leaves the coffee cup as the currents of steam and air rise.
Convection is the transfer of heat energy in a gas or liquid by movement
of currents. (It can also happen is some solids, like sand.) The heat moves
with the fluid. Consider this: convection is responsible for making macaroni
rise and fall in a pot of heated water. The warmer portions of the water are
less dense and therefore, they rise. Meanwhile, the cooler portions of the
water fall because they are denser.
Conduction is the transfer of energy through
matter from particle to particle. It is the transfer
and distribution of heat energy from atom to
atom within a substance. For example, a
spoon in a cup of hot soup becomes warmer
because the heat from the soup is conducted
along the spoon. Conduction is most effective
in solids-but it can happen in fluids. Fun fact:
Have you ever noticed that metals tend to feel
cold? Believe it or not, they are not colder!
They only feel colder because they conduct
heat away from your hand. You perceive the
heat that is leaving your hand as cold.
Radiation: Electromagnetic waves that directly
transport ENERGY through space. Sunlight is
a form of radiation that is radiated through
space to our planet without the aid of fluids or
solids. The energy travels through nothingness!
Just think of it! The sun transfers heat through
93 million miles of space. Because there are
no solids (like a huge spoon) touching the sun
and our planet, conduction is not responsible
for bringing heat to Earth. Since there are no
fluids (like air and water) in space, convection
is not responsible for transferring the heat.
Thus, radiation brings heat to our planet.
How a radiometer works: You need to focus on the
edges of the vanes to explain the behavior of the
radiometer. Heat excites the black surface of the
vanes more than it heats the white surface. Black is
a good absorber and a good radiator. Think of black
as a large doorway that allows heat to pass through
easily. In contrast, white is a poor absorber and a
poor radiator of energy. White is like a small doorway
and will not allow heat to pass easily.
The difference in temperature between the warm, black side and the cooler white side causes gasses to creep along the surface of the vanes. This effect is known as "thermal creep." The faster gasses from the black side strike the edges of the vane at an angle with more force than the molecules from the cold side. The equal and opposite forces cause the radiometer to spin.
Why a radiometer runs backwards after the light is turned off. Heat escapes quickly from the black sides of the vanes. Thus, the black molecules cool off first. Meanwhile, the white molecules take longer to lose heat cool down. The result is that gasses from the white vane push off with more force (Newton's third law) and the vanes spin in the opposite direction.
here is a great interactive site for your study about conduction, convection and radiation
http://www.wisc-online.com/objects/ViewObject.aspx?ID=sce304
http://www.wisc-online.com/objects/ViewObject.aspx?ID=sce304
Bill Nye color -- watch these 3 parts after the optics ones below - if you would like
Bill Nye Optics EXTRA!! 7E watch these as your homework and take GOOD notes on a a4 sheet of paper to hand in next class
part 1
PART 2 OPTICS
PART 3
HEAT AND ENERGY TEST REVISION
For the heat unit test you need to know the following
- transferring and transforming energy
- convection, conduction and radiation
- the difference between heat energy and temperature
- how heat energy affects the molecules
What is Sound?
Sound is a type of energy made by vibrations. When any object vibrates, it causes movement in the air particles. These particles bump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. This movement, called sound waves, keeps going until they run out of energy. If your ear is within range of the vibrations, you hear the sound.
Picture a stone thrown into a still body of water. The rings of waves expand indefinitely. The same is true with sound. Irregular repeating sound waves create noise, while regular repeating waves produce musical notes.
When the vibrations are fast, you hear a high note. When the vibrations are slow, it creates a low note. The sound waves in the diagram show the different frequencies for high and low notes.
Low frequency notes
High frequency notes
How do Wind Instruments make sound?
In wind instruments, like the flute and trumpet, vibrating air makes the sound. The air particles move back and forth creating sound waves. Blowing across a flute's blow hole sets up Slinky-like waves in the tube. In the clarinet, a vibrating reed (a thin piece of wood set in the mouthpiece) gets the waves started. Different pitches are played by pressing keys that open or close holes in the tube making the air column inside the tube longer or shorter. Longer air columns produce lower pitches.
How do String Instruments make sound?
Stringed instruments are played by pressing the fingers down on the strings. This pressure changes the strings' length, causing them to vibrate at different frequencies and making different sounds. Shortening a string makes it sound higher. Strings produce different sounds depending on their thickness.
Find out more about Sound
The Sound Site
Interactive Sound Site
Answers to Trivia Questions
Sound is a type of energy made by vibrations. When any object vibrates, it causes movement in the air particles. These particles bump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. This movement, called sound waves, keeps going until they run out of energy. If your ear is within range of the vibrations, you hear the sound.
Picture a stone thrown into a still body of water. The rings of waves expand indefinitely. The same is true with sound. Irregular repeating sound waves create noise, while regular repeating waves produce musical notes.
When the vibrations are fast, you hear a high note. When the vibrations are slow, it creates a low note. The sound waves in the diagram show the different frequencies for high and low notes.
Low frequency notes
High frequency notes
How do Wind Instruments make sound?
In wind instruments, like the flute and trumpet, vibrating air makes the sound. The air particles move back and forth creating sound waves. Blowing across a flute's blow hole sets up Slinky-like waves in the tube. In the clarinet, a vibrating reed (a thin piece of wood set in the mouthpiece) gets the waves started. Different pitches are played by pressing keys that open or close holes in the tube making the air column inside the tube longer or shorter. Longer air columns produce lower pitches.
How do String Instruments make sound?
Stringed instruments are played by pressing the fingers down on the strings. This pressure changes the strings' length, causing them to vibrate at different frequencies and making different sounds. Shortening a string makes it sound higher. Strings produce different sounds depending on their thickness.
Find out more about Sound
The Sound Site
Interactive Sound Site
Answers to Trivia Questions
- Can sound travel under the water?
Yes sound can travel under the water. It moves four times faster through water than through the air. It can travel such long distances that whales can hear each other when they are nearly a hundred miles apart. - Is there sound on the moon?
No, there is no sound in space. Sound needs something to travel through like air or water. - What is the speed of Sound?
Sound travels through air at 1,120 feet (340 meters) per second.
Interactive work
Worksheethttp://www.tryscience.org/experiments/experiments_japan_online.html
Try this aswell
http://www.nidcd.nih.gov/health/education/decibel/decibel.asp
Part of the ear activity
Go to this site http://kidshealth.org/kid/htbw/ears.html and write 3 sentences about the outer ear, the middle ear and the inner ear and their functions