AY Honors/Physics/Answer Key

1. Define the following:

a. Physics

A branch of science that deals with matter, energy, motion, charge, and force.

Physics starts with observation. We can observe the world around us with our 5 senses, or we can use a number of tools such as a balance, meter stick or ruler, clock or stop watch to provide a more accurate measurement. Galileo used his pulse to time his experiments, but a stop watch would have improved the accuracy of his measurements. Physicist also use more complicated tools as they look at more complicated events such as the colision of sub-atomic particles in an atomic accelerator. The most important tool of physics is mathematics. You can think of Mathematis as the language of physics.

b. Mass

A quantity of matter related to weight by Newton's second law of motion represented mathematically as [math]\displaystyle{ F=m \cdot A }[/math]

c. Work

A measure of energy. If we push a heavy load, then the work that we do is how hard we push the load times how far we push the load.

[math]\displaystyle{ Work=Force \cdot distance }[/math]

d. Force

An influence on an object that causes the object to move or change direction.

e. Power

How much energy expended per unit of time. If you can do lots of work quickly, then you are using more power.

[math]\displaystyle{ Power= \frac{(Work\ done)}{(time\ it\ took\ to\ do\ the\ work)} }[/math]

f. Potential energy

The energy of an object based on its relation to other objects. For example if I lift a ball above the ground by a given distance, then the ball has the potential to fall the distance that I've raised it. The potential energy of a ball can be measured by measuring how high you raise the ball against the force of gravity on the mass of the ball.

Potential energy of the ball is given by the relationship:

(E) = Mass of ball (m) * Accceleration of gravity (g) * height we rase the ball (h)

We write this [math]\displaystyle{ E=mgh }[/math]

g is the acceleration of gravity and is 9.8 m/sec/sec or 32 feet/sec/sec

We also see potential energy as the stored energy of a battery. The energy of a battery is stored chemically. It becomes kinetic energy in the form of heat and light when we turn on the switch of our flashlight.

g. Kinetic energy

The amount of energy that an object has based on its motion relative to other objects. Kinetic energy in it's simplest form is related to the speed of an object in relation to the observer. Kinetic energy in it's most complex form can be heat

The kinetic energy of a moving ball can be measured by knowing 2 things about the object

1) The mass of the object. (Determined using a balance.)

2) The velocity of the object (Time how long it takes to travel a given distance) [math]\displaystyle{ velocity=\frac{distance}{time} }[/math]

[math]\displaystyle{ \ Kinetic\ energy = \frac{1}{2} \times (Mass\ of\ object) \times (Velocity\ of\ object)^2 }[/math]

We write this as [math]\displaystyle{ E_k=\frac{1}{2} m v^2 }[/math]

h. Weight

The force that gravity exerts upon a body. According to Newtons second Law of motion:

[math]\displaystyle{ The\ weight = (mass\ of\ object) \times (local\ acceleration\ of\ gravity) }[/math]

Weight is commonly mistaken for mass, but weight could be significantly more on a planet with a larger gravity, or could be significantly less on a planet with a lower gravity. Mass on the other hand is the same in both circomstances.

i. Matter

Something that has mass. There are four states of matter: solid, liquid, gas, and plasma. Physicists tend to divide the universe up in two general categories

Energy

Matter

Enstein showed these to be related ([math]\displaystyle{ E=mc^2 }[/math])

j. Inertia

A property of matter that works against an external force. According to Newton's first law of motion, a body at rest tends to stay at rest unless acted on by an outside force. An object in motion tends to stay in motion unless acted on by a force.

k. Friction

The rubbing of the surface one object against the surface of another.

At the atomic level you can think of bumpy surface like sand paper rubbing against another surface. When the two surfaces are at rest, the high spots of one surface fit into the valleys of the other surface and it takes quite a bit of force to move one over the other. Once they are moving, the two surfaces bounce from peak to peak like a skiier only hitting the tops of the moguls. We observe that it takes more energy to start pushing an object than to keep it moving once moving.

We call these two frictional forces

1) Static Friction

2) Kinetic Friction

The energy that we loose to friction is turned into heat. Rub the palms of your hands back and forth across each other. Your hands will start to get warm, in fact this is a good way to warm your hands when it is chilly. This heat can cause problems in the fan of your computer, or the cylinders of a car, so bearings, oil and grease are used to help reduce the heat and damage that can cause from friction.

l. Wave

A disturbance traveling through a medium by which energy is transferred from one particle of the medium to another without causing any permanent displacement of the medium itself.

In a guitar string for example, the string will vibrate up and down, but the particles that form the string do not move horizonally along the string. Likewise, if you throw a pebble into the water, the water goes up and down and the wave spreads out from the splash point, but there is not a flow of liquid along the surface of the water.

m. Center of gravity

The point from which all the gravitational forces within an object appear to come. This point is the same as the center of mass in a uniform gravitational field.

n. Exponential notation

Scientific notation is a mathematical notation that makes it easier to work with very large numbers or with very small numbers. In physics it is very common to have very large numbers such as the number of atoms in a drop of water, or the number of stars in a galaxy. It is also quite possible to have very small numbers such Planck's constant (0.0000000000000000000000000000000006626068 [math]\displaystyle{ m^2 }[/math]kg/s

We write numbers in scientific notation by getting rid of the zero space holders.

In large numbers

[math]\displaystyle{ 1\times10^9 }[/math]=1,000,000,000

[math]\displaystyle{ 6.02\times10^{23} }[/math] = 602,000,000,000,000,000,000,000

[math]\displaystyle{ 2.9979\times10^8=299,790,000 }[/math]

For small numbers the exponent is negative

0.00001= [math]\displaystyle{ 1\times10^{-5} }[/math]

0.000000015=[math]\displaystyle{ 1.5\times10^{-8} }[/math]

Planck's constant = 0.0000000000000000000000000000000006626068 [math]\displaystyle{ m^2 }[/math]kg/s =[math]\displaystyle{ 6.626068\times10^{-34} }[/math] [math]\displaystyle{ m^2 }[/math]kg/s

The exponent tells us how many places we need to move the decimal point. We move it to the right for positive exponents and we move it to the left for negative exponents.

Exponential notation is used on many calculators and programming laguages. the [math]\displaystyle{ \times10 }[/math] is replaced by the letter E

We would write [math]\displaystyle{ 31E6 }[/math] instead of [math]\displaystyle{ 31\times10^6 }[/math].

o. Absolute zero

A theoretical minimum temperature at which all motion of an atom ceases.

This minimum temperature is:

0 Kelvin= -273.15° Celsius = –459.67° Fahrenheit

The coldest temperature ever was measured by a MIT team in 2003. The temperature was 450 picoKelvin. this is 450x[math]\displaystyle{ 10^{-12} }[/math] Kelvin or 450 trillionths of a degree from absolute zero.

p. Fulcrum

The support, on which a lever turns in moving a body.

The Center support of a teeter totter is the fulcrum.

2. What is the scientific method? How can the scientific method be used to study the Bible?

All science starts with observations. A biologist might observe a bird and describe its colors or actions. A chemist might note a pungent aroma. A physicist might observe an object falling. Each of these events would be an observation. We use our senses, or use machines that can increase the power of our senses.

The observation causes us to ask basic questions about the event. These questions can form the basis of a hypothesis. A hypothesis is a scientist's guess about what might explain the observations. A hypothesis is most useful if it suggests an experiment that can be done to either prove or disprove the ideas we have as to the way things work.

We do an experiment to test the hypothesis, and this leads to more observations and we start the process all over again.

We can summarize this by

observe-> hypothesis -> experiment

When an idea has been tested many times it is called a theory, and if it is tested so thoroughly that we are sure that it right it might be called a Law.

The scientific method can be applied to any field of study, and tends to be self corrective. Errors cannot stand long - when others do the experiment they will either get the same results or different results. If they get different results, then more observation, hypothoses, and experiments are needed.

The study of the Bible can be enhanced by observing a text and then experimenting based on the ideas that come from that text. For example, If you read the text in Malachi 3:10

'Bring the whole tithe into the storehouse, that there may be food in my house. Test me in this,' says the LORD Almighty, 'and see if I will not throw open the floodgates of heaven and pour out so much blessing that you will not have room enough for it'.

Your hypothesis might be that God will bless you if you return your tithe. If you take action on these thoughts and do the experiment, you can find out if it is true.

3. What is a controlled experiment?

A controlled experiment is an experiment where you try to eliminate other factors that might affect the result. Let's look at one of the most famous Physics experiments and possibly one of the most important of all time. It will illustrate how we can deal with and control the variables. The experiment was done by an Italian Scientist by the name of Galileo Galilei.

For almost 2,000 years people believed the philosopher Aristotle who said that heavier objects fall faster than lighter objects. At the time of Galileo, there was no scientific method, and so people believed Aristotle based on his authority. Aristotle's idea was more than a hypothesis, in the minds of the people this was a law of physics.

Galileo asked questions about this law. It is obvious that a feather really does fall slower than a hammer, but he hypothesized that this is because air resistance prevents a feather from falling at full speed. Instead of thinking, as Aristotle did that moving objects tend to come to rest, he thought there might be somethng holding an object back "frictional forces" that slowed the object down.

Galileo probably did not drop objects from the leaning tower of pizza, but he did experiments with an inclined plane or a ramp that he rolled objects down. This allowed him to slow down the falling action and thus minimize the "air friction". He was able to determine that objects are accelerating and that the mass does not affect the acceleration.

Galileo was able eliminate the "air friction" variable and this allowed him to "see" the underlying physics of falling bodies. He published his theories in his book entitled Discorsi e dimostrazioni matematiche, intorno à due nuove scienze (Discourses and Mathematical Demonstrations Relating to Two New Sciences) in 1638.

When designing an experiment you should try to figure out what variables might affect the experiment and then try to eliminate the variable. Sometimes the variables are not discovered until after the first or second experiment. Galileo's hypothesis was that air was affecting the falling objects.

As a demonstration drop a piece of paper and a book at the same time. Ask the students to hypothesize which will hit first, and then do the experiment. Was there hypothesis correct?

Now do the same experiment with the paper crumpled What happened?

Why?

This would be a good time to do the experiment of question 10 below.

4. Explain the terms in Albert Einstein's [math]\displaystyle{ E=mc^2 }[/math] equation.

Albert Einstein's Theory of Special Relativity was published on June 30, 1905. Most of the theory of special relativity has to do with the relation between moving objects and light that is passed between them.

Although light is a wave phenomenon, the Michelson Morley experiment of 1887 had shown that there is no medium needed for it to travel through space.

E - is the symbol for energy.

Energy is a unit of work in MKS system it is [math]\displaystyle{ Kg \cdot M^2/sec^2 }[/math] which is known as a Watt.

In the CGS system it is a [math]\displaystyle{ g \cdot m^2/sec^2 }[/math] which is known as an erg. Energy can take the

form of heat, and is measured in calories or Kilocalories when talking about heat. Calories are measured in

a calorimeter by measuring the change in temperature of water by adding heat into the system. One calorie of

heat raises one gram of water one degree centegrade. To show how mechanical eneregy or work is related to

heat energy, paddles are turned in the calorimeter and the temperature change is measured.

m- is the rest mass of a particle.

This mass could be measured in kg or grams.

c- is the speed of light.

C stands for celeritas which is latin for swiftness and is used to represent the speed of light.

299,792,458 Meters/second or 186,282.397Miles/second

2- The 2 on the right of the c represents the action known as squaring a number.

We square a number by multiplying it by itself. In this equation we are squaring a very large number which yields a very very large number :[math]\displaystyle{ 299792458 \cdot 299792458 = 8.98755179\times10^{16} }[/math]

What this equation indicates, is that mass and energy are interchangeable. Mass can become energy and energy can turn into mass. Before Einstein, there were two laws of physics

Conservation of matter- This law stated that particles of matter are not created or destroyed

Conservation of energy- This law stated that energy is not created or destroyed it just changes form

The [math]\displaystyle{ E=mc^2 }[/math] equation says that there is only one law:

Conservation matter and energy- matter and energy are neither created or destroyed

It was not until 1938 that Lise Meitner and Otto Hahn were able to split a nucleus and see that energy was released. The energy released coresponed to the mass loss according to Einstein's equation.

It was shown that an atom with a large nucleus can break into two parts, emitting a gamma ray. If the mass of the two parts were added up some of the mass was missing. The gamma ray had no mass, only energy, but the energy was equivalent to the missing mass if we use Einstein's equation.

When we are talking about very energetic particles such as gamma rays, we often see the gamma ray becoming a pair of particles and then joining again to become a gamma ray.

A gamma ray with an energy of 1.022MEV (Million Electron Volts) can spontaneously form an electon anti-electron (Positron) pair. Each particle has mass that has the equivalent energy of .511MEV and one has a positive charge and one a negative charge. Because one is negatively charged and one is positivly charged, they are likely to be attracted to each other and recombine and form a gamma ray again. The gamma ray has no charge or mass.

5. What units of measure for mass, length, and time are used where you live?

Units of Measure

System of Measure	Length	Mass	Time
English System	Foot	Slug	Seconds
SI System	Meter	Kilogram	Seconds
Metric (MKS) System	Meter	Kilogram	Seconds
Metric (CGS) System	centimeter	gram	Seconds

Most of the world uses the SI or Système International d'Unités for all measurements. It is only in the United States of America, Myanmar, Liberia, and a few other countries that the English system is used for most activities.

From a scientific point of view, it is very surprising that the English system is still in use in any technologically advanced country. Its use in the United States led to a catastrophic failure in the NASA Mars Orbiter mission of 1999. The $125 million Mars orbiter was lost because a Lockheed Martin engineering team used English units of measurement while the NASA team used the metric system for spacecraft navigation.

6. What units of measure are used for time prophecy in the Bible? What is the chapter and verse where they can be found?

A day is used to represent a year in two places in scripture:

Ezekiel 4:6

After you have finished this, lie down again, this time on your right side, and bear the sin of the house of Judah. I have assigned you 40 days, a day for each year.

Numbers 14:34

For forty years—one year for each of the forty days you explored the land—you will suffer for your sins and know what it is like to have me against you.

This is used in the prophecies of Daniel, especially Daniel 8:14

He said to me, "It will take 2,300 evenings and mornings; then the sanctuary will be reconsecrated."

Isaac Newton is known as one of the greatest physicists, but few remember that he devoted more time to the study of the Bible and alchemy than to the study of Physics, and in Observations upon the Prophecies of Daniel, and the Apocalypse of St. John. he wrote:

"The Sanctuary and Host were trampled under foot 2300 days; and in Daniel's Prophecies days are put for years: but the profanation of the Temple in the reign of Antiochus did not last so many natural days. These were to last till the time of the end, till the last end of the indignation against the Jews; and this indignation is not yet at an end. They were to last till the Sanctuary which had been cast down should be cleansed, and the Sanctuary is not yet cleansed."

7. List Newton's three laws of motion.

First law

An object at rest will stay at rest and an object in motion will stay in motion unless acted on by a force.

Experiment-You can do the experiment in question 8 of the physics honor to demonstrate inertia

Second law

The acceleration of a body is directly proportional to the force acting on it, This is written as [math]\displaystyle{ F=mA }[/math]

Experiment- Use plastic spoons and marshmellows, nuts, apples or other objects to demonstrate how the same force (the bend of the spoon) accelerates the objects wiht different mass, different distances.

How can you make sure that you get the same force each time?

Does the objects mass affect the distance it travels?

Does the mass affect the speed of the object?

Experiment-Connect a fish scale to a small weight and see what measure you get if you pull the weight slowly or quickly

Third law

For every action or force there is an equal but opposite reaction

If I push on you, then you push on me with the same amount of force, but in the opposite direction

Experiment-You can do the experiment in question 9 of the physics honor to demonstrate action--reaction principle.

8. Using a table cloth and several heavy books, demonstrate Newton's first law of motion.

Theory-

An object at rest will stay at rest and an object in motion will stay in motion unless acted on by a force.

Materials-

Table

Table Cloth

Books (various sizes)

Method-

In this experiment, we will place a table cloth over a table, and then place the books on top of the table cloth.

Questions-

What happens if you try to pull the table cloth slowly?

What happens if you try to pull the table cloth Quickly?

What happens if the books are light?

Does the type of table cloth matter? What if it is smooth like silk? or Rough like sand paper?

What does this experiment tell us about Newton's First Law of motion?

Is there another experiment that I can do to prove or disprove Newton's First Law of motion?

Spiritual Application-

9. Using an air-filled balloon, demonstrate Newton's third law of motion.

Theory-

For every action or force there is an equal but opposite reaction or force

Imagine sitting in space (no friction to hold you in place) with a brick. If you throw the brick, the brick will go away from your original location, but you will also go away from your original location (Your speed will be slower than the brick because you are much heavier than the brick). A rocket does the same thing with the molecules of the exhaust. The molecules are very light, but are traveling very fast, and thus can accelerate the rocket to very high speeds.

Material

Balloons (this is your rocket)

Drinking Straws

Tape

String

paper

scissors

Method

Provide as little guidance as possible. Let the spirit of learning quide.

Competition between two or more groups can be prompted by seeing which team can get the balloon to fly to a specific target

Once a team figures out the way to guide the balloon, then you can have races between the various teams.

Questions

If you blow up a balloon, and then let it go without tying a knot in the opening, What happens?

Does this agree with Newton's third law of motion?

How can you make the balloon go where you want it to? (guide the balloon?)

What provides the force?

Spiritual Application

When God acts, the universe reacts. We see this repeatedly in the creation story. God spoke and things appear. He says, "Let there be light" and there was light. "For every action there is a reaction"

10. Demonstrate Galileo's falling body experiment by dropping two plastic beverage bottles (one full of water, the other half full) at the same time from a height of seven feet. Record the results and draw a spiritual application from this experiment.

Theory

The Earth attracts everything to itself. We represent the Newtonian attraction with a Big G which stands for Gravitation constant (in MKS units it has a value 6.67x[math]\displaystyle{ 10^{-11}m^3/(kgS^2) }[/math] and write the equation:

[math]\displaystyle{ F = G \frac{m_1 m_2}{r^2} }[/math]

The more mass an object has, the higher the Force exerted on it, this extra force exactly cancels out the inertia of the object, so we can see no matter how big or small an object is it will experience the same accceleration of gravity specified by little g. On the Earth we will let [math]\displaystyle{ m_1= }[/math]mass of earth and [math]\displaystyle{ m_2= }[/math]mass of object which we we say is m: We can then set the Force of gravity = ma by Newton's 1st law of motion:

[math]\displaystyle{ F = G \frac{m_e m}{r^2} = ma }[/math]

Notice that we have m on both sides of the equation. So m is completely canceled out leaving us with

[math]\displaystyle{ a = G \frac{m_e }{r^2} }[/math]

G is constant, the Mass of earth [math]\displaystyle{ M_e }[/math] is constant, and near the surface of the earth, the distance from the center of the earth does not change much, so [math]\displaystyle{ r^2 }[/math] is almost a constant. This means that a is equal to a constant. We call this constant the acceleration of gravity near the surface of the Earth and represent it with the symbol g = 9.8M/[math]\displaystyle{ sec^2 }[/math].

[math]\displaystyle{ x=\frac12gt^2 }[/math]

Notice there is no mass indicated in the equation that specifies the accceleration of an object in a gravitational field.

Materials

Plastic beverage bottles

water

Method

have the class drop plastic beverage bottles and judge which hits first. Have one half full of water and the other completely full of water. Make sure the lid is screwed on tightly.

Questions

Which one hit first?

What would happen if the bottle was completely empty? Why?

Spiritual Application

In a Spiritual sense, we are all attracted by the Grace of God big G shown at the cross of Jesus. It does not matter how much Sin there is in our lives the cross of Jesus attracts us equally and overcomes all the sin no matter how much is in our lives. In Christ we are all sinless no matter how bad we have been in the past.

Galileo was able to step out on his faith that air frictions was holding back light objects such as a feather, and this is why Aristotle had said that heavier objects fall faster. He imagined a world that had no air friction, and thus was able to see the underlying physics. We must rely on faith as we look toward the heavenly kingdom and imagine a world without suffering, illness, and death.

11. Demonstrate the mechanical advantage of levers by pulling a large nail, driven deeply into a board, using only a hammer. Pull a second nail using a hammer and a small block of wood, located near the nail, under the head of the hammer. Note the difference in force required to pull the nail with different positions on the hammer on the block (fulcrum) and draw a spiritual application from this experiment.

Theory-

Simple machines are used to create a mechanical advantage. They do this by reducing the amount of force needed to accomplish a job. The list of machines usually includes the following machines

Inclined plane- It takes less force to push a load up a slope than lift it straight up.

Wheel and axle- The wheel is arguably the most important machine. It reduces the amount of frictional forces.

Lever-Is composed of a fulcrum or pivot point and a long rigid bar or beam. The closer the object that we are lifting is to the fulcrum the easier (More mechanical advantage we have.

Pulley-Is a wheel that is used with a rope to change the direction of a force. Multiple pulleys can be used together to create a block and tackle that will increase the mechanical advantage.

Wedge-This machine is just two inclined planes, but is usually included because it is so useful.

Screw-This is simply a circular inclined plane, but because it takes a rotational force and turns it into a linear force, it is almost always included in a list of simple machines.

The machine being studied here is a simple lever. The hammer handle is the lever arm, and the curve of the head forms the fulcrum. The claw of the hammer is also a wedge or inclined plane. Sometimes you use a hammer with a pry bar, nail puller or another hammer to wedge the claw under the nail head.

The Lever uses the physics principle of torque or rotational force. Torque = force*distance.

Materials-Hammer, nails, 2x4 at least 2 feet long, small block of wood

Method- Hammer in a number of nails and have the class try pulling a nail. Then demonstrate how to position the block of wood to act as a fulcrum. Have the class repeat the experiment using the block of wood.

Questions-

Start with a description or demonstration of various machines as described in the theory section. Then ask the class "what kind of machine is a hammer"

Where is the fulcrum on the hammer?

Where is the fulcrum when using the block of wood?

Which way was easier?

What difference does it make how close the fulcrum is to the block of wood?

What difference does it make where you grip the hammer? Is it easier near the head or at the end of the handle?

Spirtual Application Example- If we let the lever

References

The people behind [math]\displaystyle{ E=mc^2 }[/math]
More explanation of [math]\displaystyle{ E=mc^2 }[/math]
Newton's Law of Motion
Galileo Falling Body Experiment
Galileo Falling Body Simulator
Lever
Could Archimedes move the Earth with a lever?
Simple Machines
Absolute Zero
Physical Constants

About the Author

--Rodneyeast 14:06, 23 October 2006 (UTC)

Rodney East works with a Pathfinder Club in Glenn Ellyn Illinois, and has been involved with Pathfinder from the age of 9 when his grandmother introduced him to the stars by working on the Star honor.

He studied everything he could find on astronomy as he was growing up and finally graduated from Pacific Union College with a Bachelors degree in Physics with an emphasis in Astronomy.

He now works in the Information Technology group of the Advanced Photon Source at Argonne National Laboratory.

Rodney and Stephanie East Produced the DVD entitled "Why Knot, an introduction to knots, rope, and splices" to help teach the Knot Tying Honor. This video is available through Advent Source.