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AP Physics I: Unit 2, Dynamics Principles

Terms in this set (37)

Newton's First Law (Law of Inertia)
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Net Force = 0
When an object is at rest or in constant velocity
Inertia
The tendency of an object to resist changes in its state of motion, changes in its velocity, or acceleration.
Mass is that quantity that is solely dependent upon the ______ of an object.
Inertia
In order to begin motion...
A force must be applied
Unbalanced forces cause...
Acceleration (a change in motion)
Equilibrium
A state in which opposing forces or influences are balanced.
If the forces acting upon an object are balanced, then the object...
Must not be accelerating
Force
A push or pull interaction between two objects. Forces only exist as a result of an interaction.
Unit of Force
Newtons (N)
A force is a vector quantity because it has both
Magnitude and direction
Horizontal (or vertical) net force is balanced...
When you are not accelerating
Applied Force (Fapp.)
A force which is applied to an object by a person or another object
Gravitational Force (Fg, mg, W)
The direction of a gravitational force is always directed toward the center of the earth. It is also known as the weight of an object.
Contact Forces
Interacting objects that "touch" each other
Normal Force (Fn, N)
It is a reactionary force that prevents an object from passing through a surface. The direction of a normal force is always perpendicular to the surface, and points away from the surface.
Action-at-a-distance Forces
Forces that can have an effect on an object without touching it
Friction Force (Ff, f)
The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across it. The direction of a frictional force always resists sliding motion between the two surfaces.
Air Resistance Force (Fair.)
The air resistance is a special type of frictional force that acts upon objects as they travel through the air. It is most noticeable for objects that travel at high speeds (e.g., a skydiver or a downhill skier) or for objects with large surface areas.
Tension Force (Ft, T)
The tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled tight by equal forces acting from opposite ends. It measures the interaction between the objects.
Spring Force (Fspring)
The spring force is the force exerted by a compressed or stretched spring upon any object that is attached to it. (3rd Law)
Free-Body Diagrams
Diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation
Newton's Second Law
F = ma
a = F/m
Acceleration and Net Force
Directly Proportional
Acceleration and Mass
Inversely Proportional
Newton's Third Law
For every action there is an equal and opposite reaction.
The size of the forces on the first object _______the size of the force on the second object.
equals
The direction of the force on the first object is ________to the direction of the force on the second object.
opposite
Forces always come in _____- equal and opposite action-reaction force _____.
pairs
Internal forces
Do not affect motion of a system's center of mass
Center of Mass
The point in an object that moves as if all the object's mass were concentrated at that point
Coasting / Sliding
No motive force
Smooth
Frictionless
Rough
Frictional forces exist
Motionless / Stopped / At rest
Forces are negligible / balanced horizontally
Moved with <direction> acceleration.
Applied force > Frictional force
Constant Velocity
Forces are balanced
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