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Conceptual Physics--Chapter 5: Newton's Third Law of Motion
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Gravity
Conceptual Physics 10th e. by Paul G. Hewitt Summary of Terms, Summary of Formulas, and Terms Within the Textbook
Terms in this set (9)
Newton's Third Law
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.
Vector quantity
A quantity that has both magnitude and direction. Examples are force, velocity, torque, electric, magnetic fields, and acceleration.
Scalar quantity
A quantity that has magnitude but not direction. Examples are mass, volume, speed, and time.
Resultant
The net result of a combination of two or more vectors.
Interaction
Mutual action between objects where each object exerts an equal and opposite force on the other.
We can call one force the *action force* and the other the *reaction force*. Then we can express Newton's third law in the form:
To every action there is always an opposed equal reaction.
System
It may be as tiny as an atom or as large as the universe.
In analyzing changes in motion, Newton's second law reminds us that we must also consider the masses involved. Suppose we let *F* represent both the action and reaction force, *m* the mass of the cannonball, and *M* the mass of the much more massive cannon. The accelerations of the cannonball and the cannon are then found by comparing the ratio of force to mass. The accelerations are:
Cannon ball:
F
---- =
A
m
Cannon:
F
---- = a
M
Lift
In application of Bernoulli's principle, the net upward force produced by the difference between upward and downward pressures. When lift equals weight, horizontal flight is possible.
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