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23 Cards in this Set
- Front
- Back
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dynamics
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study of why things move
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force
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(vector) push or pull on an object measured in Newtons (N)
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Cartesian Method
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method of measuring forces using diagrams on cartesian plane using angles 0 to 360
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Navigator Method
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method of diagraming forces using direction; north/south, east/west
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net force
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the sum of all forces acting on an object in a system; as forces are vector quantities they can be added like all other vectors
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free body diagram
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- diagram that shows an object and all the force vectors acting on the object
- vectors are drawn from the centre of the object |
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INERTIA
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- the tendency for an object to maintain an unchanged velocity
- a property of all objects with mass |
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Newtons First Law
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An object with no net force acting on it moves with a constant velocity.
Fnet = 0N then change in velocity = 0m/s |
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Newtons Second Law
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The acceleration of a body is directly proportional to the net force acting on it.
The acceleration of a body is inversely proportional to its mass. Fnet = ma mass (kg) acceleration (m/s2) Force (N) |
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Newtons Third Law
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When one object exerts a force on a second object, the second exerts a force on the first that is equal in magnitude, but opposite in direction.
For every action, there is an equal but opposite action. |
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action-reaction pair
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forces come in "action-reaction pairs" involving only 2 objects.
ex. propelling yourself forward; by pushing backwards, the ground propels you forward. |
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mass vs. weight
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mass; measure of the inertia of an object, and is the same everywhere - no matter the gravity-induced environment.
weight; measure of the force of gravity acting on an object. Changes depending on force of gravity. In gravity-free environment, object is weightless. weight (Fg) = mg |
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friction
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force that opposes motion.
For 2 surfaces in contact, force of friction is parallel to the 2 surfaces, and in the opposite direction of the motion. |
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what causes friction?
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friction is caused by microscopic high points of one surface temporarily bonding - caused by electromagnetic forces - with the high points of another surface.
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static friction
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force that opposes the start of motion. In order to get an object moving, you must exert a force greater than the force of static friction.
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sliding (kinetic) friction
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force that opposes sliding motion of one surface on another. Generally less than static friction, this is the reason a car will stop faster if the tires are not skidding when brakes are applied.
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coefficient of friction (μ)
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number representing how easily one surface slides on another. the smaller the number, the easier surfaces slide. NO UNITS!
*greater the force pushing two objects together, the greater the force of friction *the more weight of an object, the greater the force of friction |
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normal force
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normal: perpendicular to...
upward force applied by a surface on an object. Perpendicular to surfaces that are in contact. Fn=-Fg |
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vertical vs. horizontal force problems
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horizontal - dealing with a force being applied, mass, acceleration, and coefficient
vertical - deals with the same, but gravity must be included |
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force problems
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are solved the same as vector quantity problems; as forces are vectors, you can resolve their vectors to find the x and y components
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equilibrium
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when Fnet = 0N
when forces in all directions are equal or balanced and the object is not accelerating. *hanging signs are at a state of equilibrium |
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equilibrant force
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a force that cancels out any existing net force and therefore, when applied, will produce equilibrium.
equal in magnitude but opposite in direction to net force. |
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ramp problems
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when dealing with ramp problems, we resolve the force of gravity into x and y components relative to the angle of the hill.
Angle between Fg and Fperp = angle of the slope |
