Term
| State, discuss, and give examples of Newton's first law of motion |
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Definition
1st--law of inertia
an object at rest and an object in motion at constant speed and sirection will remain so unless acted upon by a net external force
a=0
inertia is a resistance to an object's change in velocity
ex: pulling a table cloth out from under dishes |
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Term
| State, discuss, and give examples of Newton's second law of motion |
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Definition
2nd law--Fnet=ma, if there is a net force on a mass it must be accelerating
if Fnet=0, a=0
if you keep mass constant, F proportional to a
if you keep force constant, m proportional to 1/a
force is defined as the act necessary to make a mass accelerate lineraly
ex: pushing a block along a table |
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Term
| State, discuss, and give examples of Newton's third law of motion |
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Definition
3rd--action-reaction, forces occur in equal and opposite pairs(on and by)
ex: a--force BY earth ON moon
r--force ON earth BY moon
external force only concered with ON forces |
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Term
| Compare the velocity in the x- and y-direction for projectile motion |
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Definition
inital velocity has both x- and y-components
x-component of velocity stays constant, no a in the x-direction
Vx=VocosΘ
y-component at top Vy=0 then increase in the negative direction from that point
Vy=VosinΘ-gt |
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Term
| using velocity vectors, describe the motion of a ball in projectile motion |
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Definition
velocity has an x- and y-component
Vo also has x- and y-parts
x-component always stays constant, but y part increases, reaches 0 at the top, and increases again but in the negative direction |
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Term
| How long does it take a ball in two dimensions to reach the top of its path? One dimension? Why are they different? |
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Definition
2D: ttop=VosinΘ/g
1D: ttoop=Vo/g
Difference: Because in 1D motion v=0 at the top..in 2D motion, Vy=0, but Vx=constant, so V does not =0
have to consider the angle Θ |
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Term
| what is a free body diagram? |
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Definition
| pictorial representation used to analyze the forces acting on a body of interest |
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Term
| Are mass and weight the same thing? how is weight calculated? |
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Definition
No, mass is quantity of matter in an object or the measure of an objects inertion
weight is the mass of an object times the gravitational pull of an object
W=mg |
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Term
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Definition
| a resistance to an object's change in velocity |
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Term
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Definition
| the act necessary to make a mass accelerate lineraly |
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Term
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Definition
the force resisting the relative motion of surfaces sliding against each other
dependent on types of materials and normal force
f=µN |
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Term
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Definition
force perpendicular to a surface
force BY resting surface ON object |
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Term
| Define coefficient of friction |
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Definition
a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together
depends on the materials used |
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Term
| Why does the equation for x not have g in the equation? |
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Definition
Hooke's Law: F=kΔx
because F proportional to x, constant is spring constant, k |
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Term
| Incline at angle Θ, what are components of weight parallel and perpendicular to the incline? |
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Definition
parallel--mgsinΘ
perpendicular--mgcosΘ |
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Term
| If an object is at rest, what is known about that object? |
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Definition
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Term
| What are the forces acting on a kicked football at the top of its path? |
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Definition
| g is straight down towards earth, there is air drag (f)in the opposite direction of velocity |
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Term
| When Fnet is constant, how are m and a related? |
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Definition
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Term
| When m is constant, how are Fnet and a related? |
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Definition
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Term
| compare static and kinetic friction |
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Definition
fs is always larger than fk, it cannot be quantified except at fsmax
fk can be quantified, it stays constant
when fs reaches its maximum point, it drops off to fk then becomes a constant fk |
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Term
| What makes a car go fast? |
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Definition
acceleration is a vector, change in speed or change in direction
gas pedal, steering wheel, etc |
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Term
| Can one pull themselves up by the boot straps? |
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Definition
No, because in order to have acceleration there MUST be a net external force acting on the object
(Force on you by you cannot happen) |
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Term
| Determine the action-reaction forces for Janet, Chair, and Keyboard |
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Definition
A:Force BY janet ON chair
R:Force ON janet BY chair
A:Force BY janet ON keyboard
R:Force ON janet BY keyboard |
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Term
| When is the normal force equal to the weight of the object? Not equal? |
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Definition
On a flat surface
On an incline or when being pushed or pulled |
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Term
| Why is a box more difficult to push than pull? |
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Definition
When pushing, normal force is weight plus force component, which makes N larger
When pulling, N is mg minus force component, makes N smaller and therefore easier |
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Term
Determine your mass in kg
(1kg=2.2lb) |
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Definition
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Term
| What keeps your book from falling through the table? |
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Definition
Newton's law of motion explain it--
no a, Fnet=0, because force up (N) is equal to force down (W) |
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Term
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Definition
| means if there is a net force acting on a mass that it must be accelerating |
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Term
| If an object has zero acceleration, are there no forces acting upon it? |
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Definition
| No, there may be forces acting on it that add to zero (N and mg=0) |
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Term
| If a brick is thrown through a window, describe the forces on the brick and the window. |
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Definition
Action-Reaction forces, equal and opposite (NEVER cancel bc they act on different objects)
A:Force BY brick ON window
R:Force ON brick BY window |
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Term
| Person jumps out of an airplane with a parachute. Describe the forces acting on the person, including friction |
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Definition
| mg down towards earth, friction up from the parachute and air drag |
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Term
| Why is it a good idea to wear seat belts in cars? |
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Definition
| If you slam on the breaks, F is throwing you forwards, friction from the seat belt will be a force acting opposite the force of your body forwards |
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Term
| Measure the coefficient of friction for a block of wood on a peice of wood |
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Definition
| Fnet=ma, at constant speed Fnet=0 |
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Term
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Definition
1564-1642
evidence of experimentally discovering laws of nature
book: "Dialogue of the Two Cheif World Systems"
born in Italy, wrote in Italian and had his book mass produced, house arrest and blind for last several years of his life |
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Term
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Definition
1642-1727
discovered the laws of nature using mathematics
wrote "Principa"
elected a member of parliament, made warden of mint and introduced ridges on coins, remained active in mind and body until death but had emotional breakdowns |
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