Unit B.2 Science 10 Flashcards
Why was energy a difficult concept to define?
Because we only see evidence of energy when it does something
How did early scientists get an idea of what energy was?
The development of the concept of energy went hand in hand with the development of technologies that use energy
It was thru observing changes in these technologies that scientists started to get a clear idea of what energy was
What is chemical energy?
Chemical energy is the energy stored in the chemical bonds of compounds
What did Antoine Lavoisier realize?
That when equal amounts of different substances burned, they produced different amounts of heat
Give an example of how chemical energy can be converted to heat.
When wood burns, the energy in the cellulose molecules is released & turned into heat
What is electrical/electric energy?
Electric energy is a form of kinetic energy produced by moving charges
Who are the 5 major scientists that helped discover & invent stuff on electrical energy?
- Alessandro Volta
- Hans Oersted
- Michael Faraday
- Thomas Seebeck
- Thomas Edison
From Topic 2.1, what are the 5 major discoveries of the “electrical” scientists?
- Battery, chemical energy can be converted to electrical
- Electrical energy can produce magnetism
- Magnetism can produce electricity
- Difference in heat can generate electricity/ heat can be converted into electricity
- Electrical energy can produce light and heat energy
From Topic 2.1, what are the 5 major inventions of the “electrical” scientists and how did they figure it out?
- 1st ever battery, 2 types of metal (copper & silver) with moistened paper sandwiched in between
- electromagnet; accidently moved a wire with a current over a compass needle and it moved
- Electric generator; moved a magnet in & out of a coil of wire it produced a current
- thermocouple; made a loop out of 2 metals; heated one of the junctions and the entire loop got a current going
- lightbulb
What is nuclear energy?
Nuclear energy is the potential energy stored in the nucleus of an atom
What is the difference between nuclear fusion & fission?
Nuclear fusion = Joining of 2 nuclei
Nuclear fission = Splitting of a nucleus
Who led the way to the development of nuclear energy and what exactly did he observe?
Henri Becquerel, and he observed that atoms spontaneously disintegrate and in the process emit radiation/ radiant energy
What did scientists originally think fueled the sun?
Chemical energy but then they realized all the sun’s mass would’ve been burned/used up 5000 years ago
What is solar energy? and how do we “experience it”
Solar energy is the H-H nuclear fusion that happens in the sun. This releases nuclear energy which travels to the earth as electromagnetic radiation and is converted to other forms of energy such as heat
Who reasoned newton’s cradle and what did he reason?
Gottfried Leibniz reasoned that whatever caused the ball to move resembled a force that’s being transmitted through the balls
What did Gottfried Leibniz name energy before James Prescott joule properly named it?
Leibniz named it “vis viva”
What are the 2 types of “vis viva” that Leibniz said could be observed in nature?
- Flowing water, wind or any object in motion could be made to do work and thus has kinetic energy
- An object raised above earth’s surface has the potential to do work because of it’s position and thus has gravitational potential energy
Who is joseph black and what did he experiment, observe and state?
Joseph black stated that heat was a fluid called “caloric fluid” that flows naturally from a hot substance to a cold one
He did this by placing a cold object in hot water and then realizing the object became warm.
What did other scientists observe about heat?
Other scientists suggested that the movement of atoms within a substance determines the thermal energy of the substance.
Atoms move or vibrate more quickly in hot than cold substances. The transfer of this thermal energy from a hot object to a cold object is defined as heat.
Who were the 4 major scientists in heat energy and what did they do?
Count Rumford:
- proved joseph black’s caloric fluid theory wrong
- 1st to realize heat and mechanical energy are related
- Realized by observing canons being hollowed out and seeing how it has endless heat coming off of it
Thomas young:
- Young proved that mechanical energy had kinetic and potential energy
- He also thought that mechanical energy was related to the work a system can do.
Sadi Carnot:
- Carnot discovered that the transformation of heat into mechanical energy could only occur when thermal energy flows from a hot object to a cool object.
James Prescott Joule:
- properly substituted the term “energy” for vis viva. He argued that heat is just another form of energy
What are joule’s 2 experiments and what did they prove?
Joule’s 1st experiment is 2 masses falling and the energy transferring to kinetic energy and finally heat
Joules 2nd experiment: A wood block with Ep is falling and strikes the 2nd wood block which gains transferred kinetic energy from the 1st wood block
What is potential energy?
Energy that is stored/held
What does the type of potential energy depend on?
Depends on how the energy is stored, whether through position or elasticity or chemicals waiting to react etc.
Mass & Weight; which is the scalar quantity and which is the vector and why?
Mass is a scalar quantity: M and is measured in kg:
It’s a measure of the amount of matter that makes it up
Weight is a vector quantity & force: The weight of an object is the gravitational force exerted on it by a large body
What is the formula for weight?
Fw = mg; W→: N = kg(m²/s²)
What is the unit for gravity and it’s definition?
Gravity is acceleration due to a large body so m/s²
What has chemical potential energy?
Any substance that can be made to do work through a chemical reaction
What 2 factors does the kinetic energy of an object directly vary with and how?
Mass and speed
Double the mass = Double the kinetic energy
Double the speed = (2)² the kinetic energy
What does the conservation of mechanical energy state?
States that the total amount of energy in a given situation remains constant; Energy can be converted from one form to another but it can never create or destroy energy
“Within an isolated system, energy can change form (between potential and kinetic), but the total amount of mechanical energy remains constant.”
What does mechanical energy mean?
Energy due to motion & position because when energy is transferred to an object, it causes a change in both potential and kinetic energy at the same time
