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newton's laws
Question | Answer |
---|---|
1st law | law of inertia |
inertia | tendency of an object NOT to accelerate |
when the external force is zero... | it's acceleration i s zero |
objects in motion or rest will stay in motion or at rest UNLESS... | acted on by an external force |
mass | is a measure of inertia |
inertia | is a measure of mass |
inertia is NOT... | a measure of weight |
weight... | is a measure of local gravity on mass |
net external forces are... | vector sum of all forces acting on an object |
the net external forces are...` | F(friction), F(gravity), F(normal), F(applied) |
equilibrium... | condition in which net external forces equal zero |
2nd law | law of impulse |
impulse is... | a force acting over a time |
law of impulse is most often used for... | collisions and impacts |
the acceleration of an object us directly proportional to... | the net force acting on the object and inversely proportional to the objects mass |
F= | ma |
3rd law | law of interaction |
interaction is... | when two or more objects act on one another |
forces often exist in... | pairs |
net external force | F(gravity)= weight, F(normal)=rxn to weight, F (application)=outside force, F(friction)= rxn to outside force |
forces tend... | to work in pairs |
forces of friction | dry, fluid, lubricated, skin, internal |
dry friction | static and kinetic |
static friction | resists against movement |
kinetic friction | resists while moving |
fluid friction | mostly related to chemicals |
lubricated friction | mostly related to engines |
skin friction | introduces drag and affects airplanes and swimmers |