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MC |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces at in pairs as described by Newtonês third law. |
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ILO: |
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Each of the following situations describes some kind of motion. Identify which of Newtonês three laws of motion might best explain the motion.
a. 1st Law: Law of Inertia
b. 2nd Law: F = ma
c. 3rd Law: Action/Reaction
______ 1. A child riding without a safety restraint is propelled through the windshield of the car
when it is involved in an accident.
______ 2. Your friend lets you shoot his new shot gun and it makes your shoulder sore.
______ 3. A car on an icy road slides off the road while trying to negotiate a curve.
______ 4. After sitting in class for nearly an hour you are ready to announce that you are
suffering from tired bottom.
______ 5. A drag race is mostly all engine and tires.
______ 6. You have to walk to town after your car becomes stuck in the sand and you are
unable to push it out.
______ 7. A fighter plane uses a drag parachute to aid in stopping.
______ 8. In a fit of anger you swing your fist at the wall putting a hole in the wall and breaking
your hand.
Correct Answers:
1. a
2. c
3. a
4. c
5. b
6. a
7. b
8. c
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MC |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces at in pairs as described by Newtonês third law. |
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ILO: |
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Identify which of Newtonês laws might best explain the following situations that describe some sort of motion. Write the letter designating the law in the blank next to the description of motion. Each law may be used once, more than once, or not at all.
a. 1st Law: Law of Inertia
b. 2nd Law: F = ma
c. 3rd Law: Action/Reaction
d. 4th Law: Figs taste good
______ 1. A dummy riding without a seatbelt is propelled through the windshield of a
car when it crashes into a tree.
______ 2. You shoot a sawed off shot gun and it makes your shoulder sore.
______ 3. A spaceship launched into frictionless space requires no force to maintain constant velocity.
______ 4. When dropped from the same height, a 50 kg pumpkin hits the ground with a larger force than a 3 kg pumpkin.
______ 5. A Neanderthal punches a rock wall and breaks his hand.
______ 6. Galileo found that a ball rolling down one incline will pick up enough speed to roll up another.
______ 7. A skydiver uses a parachute to reach terminal velocity and prevent death.
Correct Answers:
1. a
2. c
3. a
4. b
5. c (a & b also apply)
6. a (b also applies)
7. a (c also applies)
MC |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces act in pairs as described by Newtonês third law. |
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ILO: |
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Throughout history people have developed elaborate explanations to describe observations of the physical world. Newton proposed simpler explanations to describe the motions of objects, subject to a few basic rules. Why have Newtonês laws achieved such importance in our current understanding of the world?
a. Before Newton, people were uneducated and superstitious. We have come to understand that their knowledge was therefore limited. We can discredit the old explanations for this reason.
b. Newton was a rich nobleman who had more time to ponder his own ideas and then had the money and prestige needed to publish his work and see that it was given importance over the old ideas.
c. We have come to understand that new ideas are generally superior to old ideas, even if it sometimes takes a long time for the new one to be accepted by everyone. Soon Einstein will be more important than Newton.
d. New ideas are accepted only after being tested and tried against observations. Newton was no exception. His ideas have stood the test of time and better alternatives have not come along yet.
Correct Answer: d
E |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces act in pairs as described by Newtonês third law. |
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ILO: |
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Both Galileo and Isaac Newton performed experiments about motion. Both men developed theories and models to explain motion of objects. In fact, Newton used many of Galileoês ideas and expanded on them to create what we now refer to as Newtonês Laws of Motion. Do some research about both menês experiments and theories, and write a 2 page report about how Newton built upon Galileoês ideas. Explain how scientific theories often build on previous ideas to expand our understanding.
Scoring Guide:
Students should include the following:
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E |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces at in pairs as described by Newtonês third law. |
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ILO: |
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There was a story told of a farmer with a very exceptional horse. The horse was used to pull a wagon to the market to sell food from the farmerês garden. Now this horse was not too unlike Mr. Ed of TV fame. This horse could talk, but he could also read and his favorite reading material was an old high school physics text that someone had left in his stall.
One day the farmer harnessed up the horse to the loaded wagon to take it to the market. At this point the horse turned to the farmer and said: –I have been reading about Newtonês laws of motion. The third law states that for every action there is an equal and opposite reaction. Now I know that Newton was on top of things and would never state an untruth. If I pull on the wagon, it will pull on me with an equal and opposite force. These two forces will be exactly equal and opposite and will therefore cancel. I will be unable to move he wagon. I refuse to move.”
No amount of argument from the farmer could convince the horse that he was wrong. The horse refused to move.
Explain the error of the horseês thinking. Use diagrams as necessary showing all forces involved on the horse and wagon.
Scoring Guide:
The solution should include a vector diagram showing the forces
acting on each body separately.
The forces acting on the horse are: the wagon pulling back, the ground pushing up, gravity pulling down, the earth pushing forward as the horse pushes back on the earth.
The forces acting on the wagon are: horse pulling on the wagon, the ground pushing up, gravity pulling down, friction of the earth opposing the motion.
In each case when the forces on that body are not in balance the body will accelerate. The up and down forces are balanced so the horse or wagon do not fall or fly. The horizontal forces are not balanced. The force forward by the horse is greater than the resistance force of friction backward and the wagon moves forward. When the force forward on the horse is greater than the resistance of the wagon and friction the horse is accelerated forward. Once in motion, the forces are balanced and the object continues without changing its motion.
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E |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces at in pairs as described by Newtonês third law. |
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ILO: |
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Two rides available at a local amusement park are the log flume and the train driven by a steam engine. We could compare the experience a rider might have on these two rides. Most would accept the fact that the log flume was a more exciting ride. Other rides become even more exciting than the log flume. Consider the giant roller coaster for example, or the looping roller coaster. We might ask the questions: –What makes a great ride?” or –Why is one ride more exciting than another?”
In terms of laws of physics consider the log flume and the train. Compare (how are they alike) and contrast (how are they different) the two rides. Draw conclusions about what makes a ride exciting. Make sure you include in your explanation what the rider feels as he/she enjoys each ride. Your explanation should include consideration of forces, energy, momentum, speed, and acceleration.
Scoring Guide:
Answers will vary. Allow one point for each comparison of things alike and things different. Answers may include but are not limited to the following:
Similar: Riders ride in a car.
Start at some point and return to that same point.
Has some circular motion at some point in the ride.
For most of the ride the speed is constant for both.
For most of each ride the rider does not experience much outside force.
Different: Log flume has high acceleration from the top of the ramp.
Because of the high acceleration the rider experience forces (F = ma).
Log flume has high negative acceleration at the bottom of the ramp.
Momentum of the rider changes drastically at the bottom of the ramp.
Potential energy at the top of the ramp is converted to kinetic energy as the log falls.
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P |
Physics |
Standard: 02 |
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Objective: 03. Explain that forces at in pairs as described by Newtonês third law. |
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ILO: |
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Water Bottle Rockets and Newtonês Three Laws
or
Newton!
Donêt Let That Rocket Fall on Your Head!
This performance task will access
your studentsê ability to:
1. Experimentally infer Newtonês three laws of motion
2. Analyze motion using Newtonês three laws
3. Create a model rocket that incorporates all three laws that
will produce a flight of at least 200'
4. Land within a 25' radius of the launch site.
Background Information
You must have taught your students
from the supplement concerning Newtonês Laws of Motion. It is helpful to have finished
the unit on Force, and started the unit on Work. Lab 1F2 is helpful in understanding pressure.
Students Must Know the
Following to Take the Test
1. The history leading to Newtonês laws of motion
2. Newtonês first law, a body will tend to stay at constant
rest or motion until acted on by another force
3. Understand the relationship between mass and inertia
4. Newtonês second law, a body will move proportional to and in
the direction of the applied force.
5. Newtonês third law, action-reaction
6. How to set up a series of experiments to find the best
results in order to solve a problem
7. How to fly 2 liter pop bottle rockets
Materials and Time Needed for a
Class of Thirty
You will need two or three weeks
from when you assign the task to completion. Students can bring their own 2 liter pop bottles. They may need two to four of them. You will need bottle rocket
launchers. These can be home made
or purchased from a science supply vendor. It is recommended to have a portable air compressor (because
of the sheer number of flights), or several bike pumps.
How to Proceed
Spend a 30 minute period in class
and introduce the task. Review
Newtonês laws. Set up your scoring
rubric with your students modeled after the one presented below. Set up clear specifications and
objectives for rocket launching heights, distances, parameters, etc. Have the students work on them at
home. Set aside two class periods,
one for experimenting, and the second for final launching. The student may do other experimenting
before or after school.
Scoring Guide
The following rubric should help
you to meaningfully and successfully score the project.
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Score |
Performance |
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4 (A) |
Rocket launch successful a. Reached a height of at least 200' b. Landed within a 25' radius perimeter c. Completed the pre-launch experiments write-up |
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3 (B) |
Rocket launch acceptable a. Reached a height of 150' b. Landed within a 50' radius perimeter c. Completed the pre-launch experiments |
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2 (C) |
Rocket launch marginal a. Reached a height of 100' b. Landed within a 75' radius perimeter c. Did at least two pre-launch experiments |
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1 (D) |
Rocket launch –...Houston we
have a problem!” minimal a. Reached a height less than 100' b. Landed outside of 75' radius perimeter c. Did one pre-launch experiment |
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0 (F) |
Rocket launch failure or no
rocket a. Did not launch b. Couldnêt land c. No pre-launch experiments |
Water Bottle Rockets and Newtonês Three Laws
or
Newton!
Donêt Let That Rocket Fall on Your Head!
Materials Needed
Two-four
2 liter pop bottles
Cardboard,
poster board, plastic etc. for fins and cones
Some mass
Water
Launcher
Air
pressure
Objectives
The student will:
1. Experimentally infer Newtonês three laws of motion
2. Analyze motion using Newtonês three laws
3. Create a model rocket that incorporates all three laws,
which will produce a flight of at least 200' and land within a 25' radius of
the launch sight.
Experimental Data Write-up
1. a. Create an hypothesis that relates Newtonês second law, to the force (air
pressure) and amount of fluid in your rocket to achieve maximum height. (Use the space below)
b. Create an experiment that will test
your hypothesis using a prototype rocket.
Remember youêll need to test for pressure and fluid type or amount
variables, therefore youêll do at least three experimental launches. (Use the space below)
c. Create a data table below that records
and helps you analyze your results.
d. Have the teacher check off each
experimental launch
e. According to your experiments, how will
you engineer your rocketês propulsion system? Draw and explain below.
2. a. Create an hypothesis that relates Newtonês second law, to the force (air
pressure) and amount of fluid in your rocket to achieve maximum height. (Use the space below)
b. Create an experiment that will test
your hypothesis using a prototype rocket.
Remember youêll need to test for pressure and fluid type or amount
variables, therefore youêll do at least three experimental launches. (Use the space below)
c. Create a data table below that records
and helps you analyze your results.
d. Have the teacher check off each
experimental launch.
e. According to your experiments, how will
you engineer your rocketês propulsion system? Draw and explain below.
3. a. Create an hypothesis that relates Newtonês second law, to the force (air
pressure) and amount of fluid in your rocket to achieve maximum height. (Use the space below)
b. Create an experiment that will test
your hypothesis using a prototype rocket.
Remember youêll need to test for pressure and fluid type or amount
variables, therefore youêll do at least three experimental launches. (Use the space below)
c. Create a data table below that records
and helps you analyze your results.
d. Have the teacher check off each
experimental launch.
e. According to your experiments, how will
you engineer your rocketês propulsion system? Draw and explain below.
Build It
Youêll have one week
Final Results
Height ________________
Landing distance ________________
Completed pre-launch write up
_____
Score___________