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Conceptual Physics Chapter 6 Newton's 2nd Law
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Gravity
A physics flash card set for Chapter 6 of Conceptual Physics by Hewitt
Terms in this set (25)
What causes an object to accelerate?
Unbalanced forces
Net force is directly proportional to
Acceleration
How does an increase in mass affect acceleration?
The result is a decrease in acceleration
Acceleration produced by a force is inversely proportional to
Mass
Inversely means
Two values change in opposite directions
Newton's second law
The acceleration produced by a net force on an object is directly proportional to the magnitude of the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object.
Equation for Newton's second law
a = F/m where a is acceleration, F is net force, and m is mass. Also written as F = ma
Force due to friction
Force created between 2 surfaces that contact each other and is in the the direction opposite to that of the motion of an object. It is mainly due to irregularities in the two surfaces. It is a force that resists motion.
What factors affect the force of friction?
The kinds of materials in contact and how much the surfaces are pressed together.
Why are both liquids and gases called fluids
Because they flow
Air resistance
The friction of something moving through air.
Free-body diagram
A diagram showing all the the forces acting on an object.
Pressure
Amount of force per unit area, P=F/A.
How does the area of contact affect the pressure a force exerts on an object?
For a constant force, an increase in the area of contact will result in a decrease in the pressure.
pascals (Pa)
Unit of measure for pressure in newtons per square meter.
Why do all free falling objects fall with the same acceleration?
All freely falling objects fall with the same acceleration because the net force on an object is only its weight, and the ratio of weight to mass is the same for all objects.
What factors determine the air resistance force on an object?
The air resistance force an object experiences depends on the object's speed and frontal area.
Air resistance force ∼ speed x frontal area
Terminal Speed
The speed at which the acceleration of a falling object is zero because friction (air resistance) balances the weight.
Terminal Velocity
Terminal speed together with the direction of motion.
Newton's second law of motion can be formally stated as follows:
...
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
...
This verbal statement can be expressed in equation form as follows:
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a = Fnet / m
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The above equation is often rearranged to a more familiar form as shown below. The net force is equated to the product of the mass times the acceleration.
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Fnet = m • a
...
;