10 Feb. Science 7 An experience with force. Acceleration. Velocity. Newton’s 1st and 2nd Laws of Motion. Momentum and Conservation. Newton’s 3rd Law of Motion.

Data from cart pulling below. Construct a graph (follow guidelines). How does the graph compare to your first prediction? Discuss.

Find the average speeds for 0-1 meters; 1-2 meters; 2-3 meters; 0-1 seconds; 1-2 seconds; 2-3 seconds. How does the average speed seem to change?

 

Think of what a scientist’s concept map of motion might look like.

Motion with a constant speed and direction = inertial motion

Motion with changing speed and/or direction = acceleration

Force is what changes inertial motion–bigger force results in bigger change

(Force is not needed to “cause” motion as is demonstrated by inertial motion.)

The resistance to change in inertial motion is inertial mass.

Velocity is speed and direction. (meters / second and a direction)

Acceleration is change in speed and direction. (meters / second / second and a direction)

Force is what causes a change in speed and/or direction. Force has a magnitude and a direction. (The force that causes 1 kg to accelerate 1 meter / second every second is called 1 Newton)

When Galileo began his work (observing a very smooth ball rolling down an inclined plane), he wondered if the speed would change with respect to distance or time.

Consider this trip:

Time (sec) Speed (km/hr)

  • 0                   0
  • 1                    10
  • 2                   20
  • 3                   30
  • 4                   40
  • 5                    50
  • 6                    60

A new kind of graph Speed (km/hr) vs. Time (sec)

What do you predict?

cartpullinga cartpullingb cartpullingc

 

Momentum is mass times velocity. Momentum has a magnitude and direction. (mass x meter / second and a direction). Momentum is conserved.

Read the following BBC article: http://www.bbc.com/news/magazine-31109732 

What parts of the article relate to ideas about velocity (speed and direction)? Explain. Express your questions.

See students visual explanations of the air-pressure water rocket.

figure8 genrktexp What do they suggest about Newton’s 3 law of motion and conservation of momentum?

 

 

 

 

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