"EXPLORING THE INTERNET: ROLLER COASTER PHYSICS"

ONE TWO THREE ISAAC NEWTON AND ME

Exploration Three

Can You Budge Me?

PURPOSE:

What force does an object exert when a force is applied to it?

RESOURCES/MATERIALS: Part Three

• Spring scales
• Rope (at least 5 meters)
• Hovercraft, air supply and extension cords (or skateboards)
• Meter sticks/rulers

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  ACTIVITIES AND PROCEDURES: Part Three

  1. Take a spring scale and devise a method that allows you to apply a given force to your scale EVEN IF you can not see the numbers.
  2. Hook your spring scale to your partner's spring scale.
  3. Cover the surfaces of the scales with a paper folded like a tent.
  4. Each of you apply a force and predict what your scales will read.
  5. Record forces applied, predictions and actual readings.
  6. Try several combinations of forces. Record the results in a data table.
  7. Place a third scale between the other two. Repeat your procedure from above. Record your results.
  8. What conclusion can you state about the forces applied from both ends?
  9. Take two Hovercraft or skateboards and the rope.
  10. Use two people, one on each craft, and the rope to experiment with the relative motion of each when the rope is pulled. Describe the experimental procedure that was used and the results obtained. AGAIN A DATA TABLE IS ADVISED!

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  Three down and you're ready to apply Newton's Laws of Motion to flight.

  Have the students give their statements regarding Newton's First Law of Motion. Then show portions of the Mechanical Universe tape Inertia.

  Hopefully they will state something that resembles " Things in motion tend to remain in motion and things at rest tend to remain at rest." If they have any parlor tricks that demonstrate the first law of motion have them do them or at least describe them.

  1. How were you able to change your state of motion, whether you were at rest or already in motion?

     A force had to act on an object to change the motion.

  2. Have you ever heard of the term INERTIA?

  3. LARGE OBJECTS HAVE A LARGE INERTIA AND SMALL OBJECTS HAVE SMALL INERTIA. What do you think that inertia means?

     The tendency for an object to stay at rest or once moving to keep moving to keep moving is called INERTIA.

     HAVE STUDENTS GIVE EXAMPLES FROM EVERYDAY EXPERIENCES OF INERTIA.

  4. Did the eggs have inertia?
     YES

     What force acted on the cardboard to set it in motion?

     THE BROOM

     What force acted on the eggs after the cardboard was removed?

     GRAVITY

     What happened to you as you sat on the hovercraft and then started the air source?

     How were you able to change you motion?

     Students begin motion as soon as the frictional force is diminished by the air. Any slight motion will produce an unbalanced force that will start them moving.

     What would you say to a 6th grader to explain Newton's 2nd Law of motion?

     Acceleration of an object increases as the force causing the acceleration increases. OR For a given force the smaller the object the faster its speed changes. Students very often do not understand the term acceleration. They will memorize the definition, but have no physical understanding for the term. Show portions of the Mechanical Universe tapes Newton's Laws.

     
     

     Placing them on a hovercraft or skateboard and accelerating them sheds a whole new light on the term. Having them watch the motion of their lab partner as that partner pulls on them with a constant force reinforces the notion that acceleration is the continual increasing of velocity.

     What did you vary when experimenting with the hotwheels setups?

     Hopefully mass and angle of the track, which alters the force.

     What did you find?

     That the steeper the track the faster the car went down the incline and that if the track height was maintained the smaller cars went faster.

     Have students make a rough sketch of a force versus acceleration graph would look like and a sketch of what a force versus mass graph would look like. If they can sketch a direct relationship for F vs a and an inverse or decreasing curve for F vs mass then they some understanding of F=ma.

     When you were sitting on the hovercraft what was the difference between being pulled with a constant force as in part 2 and being pulled or pushed and then let go as in part 1?

     Your body perceives accelerating forces but not uniform motion.

     If you applied two newtons to your scale and your lab partner applied two newtons to his or her scale what reading would you get? What about a combination of three and four?

     Students have a great deal of difficulty with predicting the correct reading on two attached scales. It is harder with three. Be certain that the have the experiences to develop the notion of equal and opposite forces with the scales.

     Where did you meet your lab partner when you alone pulled on the rope?

     Approximately the middle of the distance between them.

     Where did you meet your lab partner if he or she pulled on the rope?

     Approximately the middle. Same place as before.

     If both of you pulled on the rope, where would you meet?

     The same place as before the only difference is the speed at which they met.

     Newton's 3rd Law is called the ACTION REACTION LAW.

     What does that mean to you.

     How would this law be significant in space travel?

     Action Reaction governs the propulsion of the shuttle into low Earth orbit.

     Skylab experiments and shuttle footage show action reaction very well, especially the OMS burn footage.

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     SPACE: NEWTON'S FINAL FRONTIER

     Roller Coaster Physics