Newton’s 2nd Law of Motion or… - Science A 2 Z



Newton’s 2nd Law of Motion or…

F=ma and the Stomp Rocket

Background information retrieved 4/22/2009:



© 2009 Barbara J. Shaw Ph.D., Science A to Z

Permission is granted to make and distribute copies of this lesson plan for educational use only.

Concepts Addressed: Physics: 3 Laws of Motion, Scientific Investigation

Lab Goals: Students will perform a scientific inquiry investigation suitable for scoring.

Lab Objectives: Students will

▪ Develop a hypothesis based on the question: Which will go farther, a stomp rocket with no additional weight, or a stomp rocket with 10 pennies?

▪ Test their hypothesis by collecting data on the light and heavy stomp rockets

▪ Produce a graph from their data collected

▪ Answer their question of which stomp rocket will go farther

Benchmark(s) Addressed:

Oregon Science Standards:

Third Grade

3.2 Interaction and Change: Living and non-living things interact with energy and forces.

3.2P.1 Describe how forces cause changes in an object’s position, motion, and speed.

3.3 Scientific Inquiry: Scientific inquiry is a process used to explore the natural world using evidence from observations and investigations.

3.3S.1 Plan a simple investigation based on a testable question, match measuring tools to their uses, and collect and record data from a scientific investigation.

3.3S.2 Use the data collected from a scientific investigation to explain the results and draw conclusions.

3.3S.3 Explain why when a scientific investigation is repeated, similar results are expected.

Fourth Grade

4.1 Structure and Function: Living and non-living things can be classified by their characteristics and properties.

4.1P.1 Describe the properties of forms of energy and how objects vary in the extent to which they absorb, reflect, and conduct energy.

4.3 Scientific Inquiry: Scientific inquiry is a process of investigation through questioning, collecting, describing, and examining evidence to explain natural phenomena and artifacts.

4.3S.1 Based on observations identify testable questions, design a scientific investigation, and collect and record data consistent with a planned scientific investigation.

4.3S.2 Summarize the results from a scientific investigation and use the results to respond to the question being tested.

4.3S.3 Explain that scientific claims about the natural world use evidence that can be confirmed and support a logical argument.

Oregon Mathematics Standards:

Third Grade

3.2 Number and Operations, Algebra, and Data Analysis: Develop understandings of multiplication and division, and strategies for basic multiplication facts and related division facts.

3.2.4 Apply increasingly sophisticated strategies based on the number properties (e.g., place value, commutative, associative, distributive, identity, and zero) to solve multiplication and division problems involving basic facts.

3.2.5 Apply the inverse relationship between multiplication and division (e.g., 5 x 6 = 30, 30 ÷ 6 = 5) and the relationship between multiples and factors.

3.2.7 Analyze frequency tables, bar graphs, picture graphs, and line plots; and use them to solve problems involving addition, subtraction, multiplication, and division.

Fourth Grade

4.1 Number and Operations: Develop an understanding of decimals, including the connections between fractions and decimals.

4.1.1 Extend the base-ten system to read, write, and represent decimal numbers (to the hundredths) between 0 and 1, between 1 and 2, etc.

4.1.3 Determine decimal equivalents or approximations of common fractions.

4.1.5 Estimate decimal or fractional amounts in problem solving.

4.2 Number and Operations and Algebra: Develop fluency with multiplication facts and related division facts, and with multi-digit whole number multiplication.

4.2.1 Apply with fluency multiplication facts to 10 times 10 and related division facts.

4.2.2 Apply understanding of models for multiplication (e.g., equal-sized groups, arrays, area models, equal intervals on the number line), place value, and properties of operations (commutative, associative, and distributive).

4.2.3 Select and use appropriate estimation strategies for multiplication (e.g., use benchmarks, overestimate, underestimate, round) to calculate mentally based on the problem situation when computing with whole numbers.

4.2.4 Develop and use accurate, efficient, and generalizable methods to multiply multi-digit whole numbers.

4.2.5 Develop fluency with efficient procedures for multiplying multi-digit whole numbers and justify why the procedures work on the basis of place value and number properties.

4.3 Measurement: Develop an understanding of area and determine the areas of two-dimensional shapes.

4.3.4 Determine the appropriate units, strategies, and tools to solving problems that involve estimating or measuring area.

Materials and Costs:

List the equipment and non-consumable material and estimated cost of each

Item $.Cost

Stomp Rocket Launcher and 2 Rockets 15.95

Additional Rockets (2/$4.95 x 10) 49.50

Hex nuts, pennies, or other heavy small objects. 10.00

Steel tape measurer 8.95

Orange cone (4/4.99) 4.99

Orange marker disks (4/4.99 x 5) 24.95

Estimated total, one-time, start-up cost: $114.34

List the consumable supplies and estimated cost for presenting to a class of 30 students

Item $.Cost

Copies of data sheet from school

Copies of graph from school

Color pencils (12 pack/1.75 x 5) 8.75

Recycled paper (for wadding in the rocket) from school

Estimated total, one-time, start-up cost: $8.75

Time:

Preparation time:

• order stomp rockets

• copy data sheet and graph

Instruction time:

• Introduction to the 3 laws of motion (suggestions for those lessons follow) 60-90 minutes

• Collecting Stomp Rocket data ~30 minutes

• Analyzing data, drawing graphs, and answering question using data 30-45 minutes

Clean-up time:

• Collect cones and disks

• Retrieve and store stomp rockets and launcher

Background:

Newton's laws of motion are three physical laws that form the basis for classical mechanics, directly relating the forces acting on a body to the motion of the body. They were first compiled by Sir Isaac Newton in his work Philosophiæ Naturalis Principia Mathematica, first published on July 5, 1687. Newton used them to explain and investigate the motion of many physical objects and systems. For example, in the third volume of the text, Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion.

First law

There exists a set of inertial reference frames relative to which all particles with no net force acting on them will move without change in their velocity. This law is often simplified as "A body persists its state of rest or of uniform motion unless acted upon by an external unbalanced force." Newton's first law is often referred to as the law of inertia.

Second law

Observed from an inertial reference frame, the net force on a particle of constant mass is proportional to the time rate of change of its linear momentum: F = d(mv)/dt. This law is often stated as, "Force equals mass times acceleration (F = ma)": the net force on an object is equal to the mass of the object multiplied by its acceleration.

Third law

Whenever a particle A exerts a force on another particle B, B simultaneously exerts a force on A with the same magnitude in the opposite direction. The strong form of the law further postulates that these two forces act along the same line. This law is often simplified into the sentence, "To every action there is an equal and opposite reaction."

In the given interpretation mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities. This is the most common, but not the only interpretation: one can consider the laws to be a definition of these quantities. Notice that the second law only holds when the observation is made from an inertial reference frame, and since an inertial reference frame is defined by the first law, asking a proof of the first law from the second law is a logical fallacy. At speeds approaching the speed of light the effects of special relativity must be taken into account.

Stomp Rockets (30 minutes)

• Before you go outside, ask your students to predict if the light or the heavy rocket will go further.

• Each student needs to bring a pencil and their data sheet. You will need to go outside for the experiment. (As an alternative, you can make arrangements to use the gym, but you will need exclusive use of it.)

• Ask students to measure out the 100 meters: mark the launch pad line with 2 cones, the 50 meter mark with a cone, and the 100 meter mark with a cone. Mark every 5 meters with a marker disk.

• Experiment (gather all students for these directions):

o Tell the students that you will give them some time to learn how to launch their rockets, and they MUST use the light rockets.

o When they have mastered stomping, begin the experiment.

o Each student will launch both light and heavy rockets 10 times (although the data sheet allows for 12 trials).

o When EVERYONE has finished launching their rockets, each student will record how far their own 2 rockets traveled.

o Each student records how far their rocket travelled.

o Repeat for trial number 2. Continue until all 10 trials are completed.

o Each student returns THEIR OWN rockets.

o If a rocket gets lost (trees love to eat them, so try to find open playground to conduct this experiment – away from the school), that is okay. However, if the student is being lazy, do not accept that.

• Give each set of partners 1 stomp rocket launch pad. Instruct students how to set up the launch pads.

• Collect Data

• Return all equipment to tub and go back to classroom.

• Students will analyze their data. Hand out the graph paper and ask students to find the total distance of the light and the heavy rocket. Explain how the students can find the average. To plot the data, the student will pick two different colors, one for the light rocket and one for the heavy rocket (for example, yellow and orange respectively. Starting with the light data (yellow color pencil), the student will record the number of meters that rocket traveled (Y axis) under trial number 1 (X axis). Repeat with trial number 2, and so on until the light rocket trials are completed. Do the same thing for the heavy rocket with the orange color pencil. Connect the yellow dots with the yellow color pencil and the orange dots with the orange color pencil. Ask the student to write a paragraph to explain the graph. Which rocket traveled further. How much further on average. Do your data always support this?

Suggestions for introducting the 3 Laws of Motion:

This lesson plan is designed for 90 minutes working with your students.

For each pair of students:

• Activity 1:

o 2 tiny skateboards

o 2 bags of sand

o 2 cups

o 2 Smithsonian cards

• Activity 2:

o 1 ramp

o 1 pencil (teacher kit)

o 1 scotch tape

o 2 finger skateboard

o 2 plastic dinosaur

o use 1 cup with sand from experiment 1

• Activity 3:

o 2 transparent tops with free rotating paper inside

o additional tops

• Activity 4

o 1 playdoh

o 1 ruler

o 2 finger skateboards

o 1 ramp

o 1 cup with sand

• Activity 5:

o 1 Pendulum

o 1 Plumb

o 2 Baggies of sand

o 1 Sheet of paper

• Activity 6 (paint inside tub optional)

o 2 Scissors (teacher kit)

o 1wooden disk top

o 1 food coloring box

o 1circle template

Set up demonstration:

• Frictionless plate

• Bicycle wheel

• Skateboard

The Demonstration

Third Law of Motion: Action/Reaction – 5 to 7 minutes

• When students enter, select four people to help you participate. For demonstrations, you need to be aware of the following:

o Select different people each week. If you need to, record who participated each week, to make sure every child in your class has the opportunity to be selected.

o Keep gender in mind and try to have equal numbers of each gender. If you need an odd number of volunteers, pick one gender this week, and two next week.

o Keep ethnicity (race) in mind. If your class is 2/3 Latino, be sure to select 2 Latinos.

o When you select your students, be aware that girls are often relegated to the inactive volunteer (holding, watching, etc.) rather than the active volunteer (thrower, jumper, etc.) Be sure to balance out the active participants between boys and girls and among the different ethnicities.

o We endeavor to provide equal opportunities for all our students, but sometimes we are totally unaware of only selecting girls to hold because of your culture. We therefore just need to keep track of these things.

• Ask one student to stand on the frictionless plate.

• Ask one student to stand on the skateboard.

• Ask one student to hold the bicycle wheel (select the strongest child with the longest arms for the bicycle wheel)

• Ask one student to stay with you to be the “pushy” volunteer.

• Ask the “pushy” volunteer to gently push the child on the frictionless plate so they begin to rotate. Ask them to stop without stepping off the plate.

• Ask the student with the skateboard to stand on it next to the student on the frictionless plate. (You must be on a hard surface – not a carpet.) Ask the student on the skateboard to push the student on the frictionless plate in a circle (pick a shoulder). Be sure to position the skateboard student so they are in a straight line to the frictionless plate student’s shoulder. Ask the class what will happen to the person on the frictionless plate. Ask them what will happen to the person on the skateboard.

• Afterwards, point out to the class that the skateboard person also moved backwards.

• Ask the two students to sit down, after collecting the frictionless plate and skateboard.

• Ask the student with the bicycle wheel to step on the frictionless plate and hold the wheel out, being sure that it does not touch any part of their clothes or body.

• Ask the “pushy” volunteer to spin the bicycle wheel as fast as they can. The student will need to build up the speed by pushing several times, until the wheel is spinning as fast as the student can make it go.

• Ask the student on the frictionless plate holding the bicycle wheel to tilt the wheel. This will cause the volunteer to start spinning in one direction. Ask them to tilt the wheel in the opposite direction. They will start spinning in the other direction.

• Ask the class to thank all the volunteers today with a round of applause.

Introduction to Concepts in Motion

Sir Isaac Newton’s Three Laws of Motion:

In this introduction, you discuss with your students that they will be exploring the three laws of motion as described by Sir Isaac Newton in 1687 and around for ~320 years. They are:

• First Law – Inertia

• Second Law – F=ma

• Third Law – Action/Reaction

BRIEFLY describe what each of those laws mean. Ask students which of the three laws was demonstrated with the frictionless plate, skateboard, and the bicycle tire (third law, although all three are in play).

We will be using different delicate scientific instruments to further explore these three laws.

First Law of Motion: Inertia

Pennies in the cup (5 minutes)

• Ask students to keep the sand in the bag, and put the bag into the cup, put the card on top of the cup and the tiny skateboard in the center of the card.

• Direct the students to flick the edge of the card.

• What happens to the tiny skateboard?

• Inertia: an object at rest (the tiny skateboard) remains at rest until a force (gravity) acts upon it and drops it into the cup of water. Students may want to repeat this activity. Allow them one more try.

• Ask students to put tiny skateboards, cards and the cups with sand into the container. As you go around collecting the tubs, be sure to move one cup with sand out for each group for the next activity.

Dinos and Skateboards (15 minutes)

• Ask the students to get the ramp, cup with sand, pencil, mini-skate board, and plastic dinosaur.

• Place the ramp on the edge of the cup (they can use a little of the playdoh to secure).

• Tape the pencil on the table about 4 inches away from the end of the ramp so that it forms a T to the ramp. It will act as a barricade to the skateboard, stopping it suddenly.

• Students place their dinosaur on the skateboard at the top of the ramp and let go. What happens to the dinosaur when the skateboard hits the pencil?

• Inertia: an object in motion continues at a constant velocity in a straight line until a force acts upon it. The dinosaur continued to move after the skateboard stopped until gravity and friction stopped the dinosaur also.

Tops (5 minutes)

• Ask students to put away the cups, ramp, dinosaur, mini-skateboard, and pencil (tossing the tape) and get out their tops.

• Ask them to notice that the paper inside the top spins freely.

• Ask students to predict what will happen to the paper when they first spin the top? What happens to the paper when they suddenly stop the top?

• Students will spin top, notice that the paper lags, then begins to spin with the top. Notice that if they stop to top suddenly, the paper inside continues to spin.

• Ask students to spin the top, stop it and spin it in the opposite direction. The paper will spin in one direction, continue to spin with then top is stopped, pause as the top spins in the opposite direction, and then begin to spin in the opposite direction.

• Inertia: This demonstrates both an object at rest and an object in motion.

• Optional: there are 4 different tops. At this point, you can bring them out for additional work of motion in a circle, or use them at the end if you have time.

• Optional: large wooden disk tops: Direct the students to cut out the template circles (to be added to kit when the tops arrive)

• Students punch a hole in the paper where the stem on the top is located, and push the paper done until it is laying flat on the top of the disk of the top.

• Students spin the top INSIDE the tub, and squeeze on drop of food coloring by the stem on the paper. (You can allow students to add one drop of each color. Allow the top to stop on its own.

• What direction did the food coloring move (in a straight line). If you use thicker paint for instance tempera, friction will cause it to be pulled more into a spiral. Also very cool.

Second Law of Motion: F=ma

Skateboard and Playdoh (15 minutes)

• Ask the students to put away their top and get the mini-skateboard, ramp, cup with the bag of sand, ruler and playdoh, and set-up their ramp again. Suggestion: if the floor is hard (rather than carpeted) instruct the students to set up the ramp on the floor. Be sure there is plenty of space for the skateboard to travel.

• Students let their skateboard run down the ramp and measure how far it travels before stopping.

• Students use all their playdoh, and shape it to fit the skate board. Ask students to predict whether the skateboard will travel further, or not as far with the playdoh.

• F=ma: This demonstrates that increasing the mass while keeping the force the same (gravity down the ramp) will decrease the acceleration (which translates to how far the skateboard can travel). The lighter skate board (less mass) with the same force (gravity) will have more acceleration (which translates to how far the skate board travels).

Third Law of Motion: Action/Reaction

Pendulums (5 minutes)

• WARN students not to swing the plumb of the pendulum until instructed.

• Instruct students to pour the sand into the base of the pendulum, smooth it, and attach the plumb.

• Ask students to predict if the pendulum will strike the arm of the pendulum on the back swing if they release it (not push it) pressed against the arm.

• After everyone has made a guess (show of hands), allow both partner to conduct this test (2 trials). Have students raise their hands if it touch. Have students raise their hands if it didn’t touch.

• Instruct the students to allow the pendulum swing and watch the decreasing movement. They can track it in the sand.

• Action/Reaction: Why did the pendulum stop swinging? What would be different if the pendulum were 18 feet instead of 18 inches tall? (It would swing longer, the strokes would be longer, but the principle of the pendulum reaching to but not going further on each swing.

• To clean up, ask the students to remove the plumb, pour the sand on the paper, form the paper as a funnel, and pour half the sand into one baggie, and the other half in the other baggie. (Depending on the abilities and self management level of your students, you may instruct them to remove the plumb, and leave everything else on their tables. After the class is over, you put the sand away.)

Stomp Rocket Data Sheet

I predict that the ___________________________________________ rocket will go further.

|Student Trial |Distance – Light |Distance – Heavy |

|1 | | |

|2 | | |

|3 | | |

|4 | | |

|5 | | |

|6 | | |

|7 | | |

|8 | | |

|9 | | |

|10 | | |

|11 | | |

|12 | | |

|Total | | |

|Average | | |

-----------------------

Trials

Distance the Rocket Traveled

Will the heavier or lighter rocket travel farther?

* Lighter Rocket weighed ________

* Heavier Rocket weighed ________

1

2

3

4

5

6

7

8

9

10

12

11

150

145

140

135

130

125

120

115

110

105

100

95

90

85

80

75

70

65

60

55aveled

Will the heavier or lighter rocket travel farther?

‪ Lighter Rocket weighed ________

‪ Heavier Rocket weighed ________

1

2

3

4

5

6

7

8

9

10

12

11

150

145

140

135

130

125

120

115

110

105

100

95

90

85

80

75

70

65

60

55

50

45

40

35

30

25

20

15

10

5

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