|Physical Science||Motions and Forces 7B1.00||Unifying Concepts of Science||Scale and Model 2.1 ad|
CONTENT STANDARD: Physical Science
CONTENT TOPIC: Motions and Forces
CONCEPT: Matter and energy in the universe are governed by physical laws.
CONTENT OBJECTIVE: 7B1.00 To understand the laws of motion
INSTRUCTIONAL OBJECTIVES: The learner will:
OUTLINE OF CONTENT:
TN COMPONENT OF SCIENCE: Unifying Concepts of Science
BENCHMARK: Models are often used to represent concepts of various magnitudes.
2.1d The scale chosen for a model determines its effectiveness.
BENCHMARK: The usefulness of a graph paper drawing is determined by the scale utilized.
Newton's first law of motion is also called the Law of Inertia. Inertia is the tendency an object has to resist a change in motion or position. All matter has inertia. Your inertia will keep you sitting in your seat unless a force pushes you out or you voluntarily decide to move. The first law states that an object at rest will remain at rest or an object in motion will remain in motion unless acted upon by an outside force. An example of this law is a car traveling down the road at 45 mph with you as the passenger. The driver suddenly applies the brakes and you move forward toward the dash continuing in the direction in which you were moving.
The second law of motion concerns the amount of mass of the object and the amount of force. It states that the greater the mass of an object, the greater the amount of force needed to move the object. In addition, the greater the mass, the less the acceleration of the object once it moves. This law has the formula which says force equals mass time acceleration. The unit of force is the newton (named after Sir Isaac Newton) which equals a 1 kilogram mass moving at a speed of 1 meter per second every second. Here is an example of Newton's second law: Imagine two shopping carts, one empty and the other one full. Which cart takes more force to get it in motion? (Full cart)
The third law of motion is probably the most popular of the three laws. It is also called the Law of Action and Reaction. This law states that for every action there is an equal, but opposite, reaction. There are numerous examples of this law. For example, when you fire a gun, the bullet goes in one direction, and the gun goes backward in the opposite direction.
2. To demonstrate the second law of motion have students attach a spring scale to an empty box first and pull along the floor for a distance of 5 meters. Then fill the box with books or blocks and have students repeat the process. This could be done several times varying the number of blocks or books and the results could be graphed. (Let the number of books be X axis and Force in newtons be the y axis.)
3. To demonstrate the third law of Motion, blow up a balloon but do not tie the end. Release the balloon and have students explain how this demonstration illustrates the third law.
Example: Determine the amount of force necessary to accelerate a 1500 kilogram car at a rate of 15 m/s2.
F = ma
F = 1500 Kg x 15 m/s2
F = 22,500N (newtons - Remember 1N = 1 Kgm/s2)
(Have students classify a list of examples for the laws.)
a. stepping from boat to shore (3rd law)
b. the funny feeling in your stomach when the elevator moves too quickly (1st)
c. A 50 pound boy and a 150 pound man sit on the floor. Which takes more force to move? (2nd))
Then you want to perform several experiments to try to prove or disprove your hypothesis. During the experiments it is vitally important that you make several observations of what occurs. These observations can be done using the five senses (except we never taste anything in the laboratory) or by measurements or preferably both. Measurements might include size, temperature, volume, etc.
The observations you make are called data. It is important that you record on paper the data taken during an experiment. From the data you collect and that collected by others, you should be able to form a conclusion that will either support or not support your hypothesis. It is okay if your hypothesis is incorrect, scientists do not always answer a problem with the first experiment.
(Divide the class into groups depending on how many thermometers and glasses or beakers you have. Have all students do the following experiment:
1. Put a specified amount of water into the first glass or beaker. Take the initial temperature. Record.
2. Set the glass down into a much larger container. Surround it with ice and add some salt to the water. Place the thermometer into the water.
3. Place the thermometer into the water.
4. Record the temperature every minute until the water freezes.
5. Graph the data and draw the curve.
6. Form a conclusion using your data. (Conclusion: salt lowers the freezing point of water)
(Students will find that the more salt added, the lower the freezing point will be.)
force - a push or pull
friction - a force that oppose motion
hypothesis - educated guess
inertia - tendency of an object to resist a change in position or motion
newton - a unit of force equal to 1 Kgm/s2
This is the time this file has been accessed since 04/02/98.
The University of Tennessee at Martin is not responsible for the information or views expressed here.
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