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objects at rest, stay at rest and objects in motion will contiue with constant velocity.
no net force = no acc. |
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Fnet=ma
when Fnet=0, object not acc, but could still be moving |
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force of grav eq.
force of grav on incline eq. |
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Fg=mg=w
Fg= mgsinθ -parallel to horitontal
Fg = mg cosθ - perp to horiztontal |
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Fgrav= G(Mm/r2)
G=grav constant: 6.7 x10-11 N.m2/kg2 |
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| for kinetic friction, its magnitiude is proportional to what? |
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| the magnitude of the normal force |
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| Force of kentic friction eq. |
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Ff = μkFN
*only magnitude based |
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| max force of static friction eq. |
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| Center of Mass for Point Masses |
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| xCM=m1x1 + m2x2..../m1 + m2.... |
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| xCG = w1x1 +w2x2..../w1 + w2 |
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| an object moving in a circular path executes uniform circular motion if what is occuring to it's speed? |
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T=rFsinθ=lF
l - lever arm
r- distance between pivot point and force of application |
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| Work by a constant Force across a horizontal plane. at an angle. |
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W = Fdcosθ
θ - angle between F and d
W in Joules (J) |
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| Power eq. in realtion to work |
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P = W/t
work over time
P in Watts (W) |
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KE = 1/2mv2
KE in joules (J) |
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| equation for power expended by air resistance on a falling object |
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P = Fv = -mgv
v-velocity
neg sign because force is opposite direction of velocity |
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| Which has the higher value? The work done by gravity on a falling object, or the work done by air resistance? |
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work done by gravity.
because:
Wbygrav=mgh
while work done by air resistance is negative, since it works in the obosite direction of velocity. |
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| equation for gravitational potential energy and it's unit of measure |
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PEgrav = mgh
in joules (J) |
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| Why is air resistance ignored when a compact object falls a very short distance? |
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The speed of the object remains small.
air resistance is small during the fall over a very short distance because the falling speed is low. Therefore, the resistance force, which is proportional to v2 is also low. |
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| What would a graph look like that showed the relationship between the distance fallen from rest as a function of time for an object experiencing air resistance? |
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| If given an objects speed traveling in a circule, and length of the axis, how would you determine the period of the objects circular motion? |
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The period is given by:
T=2∏/ω
and the angular velocity is given by:
ω=v/r
because v and r is given, the ω value can be solved and plugged in to determine T. |
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| What causes an object to experience an artificial gravitational acceleration in a rotating space station? |
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| The object's propenstiy to move in a striaght line while the space station forces it onto a curved path. |
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| The work done by a force that acts over a displacement is given by the equation: |
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| relationship between work and kinetic energy (eq) |
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| equation for determining power when energy expended is given. |
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P = E/t
power = energy/time |
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| give the equivalent of a watt using kg, m, and secs. |
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| watt = joule/s = kg.m2/s3 |
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| if given an object's constant velocity and the constant force necessary to acheive this, which equation would you use to calculate power? |
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| If an object is moving with a constant velocity of 5 m/s, what is the power needed to maintain motion? |
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| none. since no force is required to keep the object moving with a constant velocity, ther is no work done, and thus, no power output. |
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| equation for total momentum before and after collision if items stick together |
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p=p'
mAvA + mBvB= (m+m)v'
momentum before = moment after |
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| is sinΘ or cosΘ used when the angle is perp or parallel to horazontal? |
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perp = cosΘ
parallel = sinΘ |
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| if two objects have equal, but opposite momenta before collision, and the combined object has zero momentum afterwords, which equation can be used to determine the ratio of the masses of the objects? |
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Definition
mAvA = mBvB
vA/vB = mA/mB |
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| If 800 J is expending to lift a block to height h, and a pully system is then used that would half the input force that would be needed, how much work would be needed to lift the block to height h? |
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| 800J. machines don't reduce the amount of work required. the work done is a fixed rate. |
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| conservation of energy equation |
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Definition
Ei = Ef
KEi + PEi = KEf + PEf |
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| If two hockey pucks, each with a nonzero velocity, slide towards eachother on a surface of frictionless ice and collide head on, will momentum and kinetic energy be conserved? |
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| momentum will be conserved, but kinetic energy would not. |
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| if an object is traveling at a constant speed down an incline of angle Θ, and a constant horizontal force keeps the object at this pace, what equations would be used to determine that force? |
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| how much gravitaional energy is lost when a 10kg object is droped and reaches a speed of 30 m/s? |
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4500J. because -PE=KE,
KE=1/2mv2. solve. |
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| if the mass of an object increases by a factor of 4, by what factor will the velocity increase (if the object is being dropped) |
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| it won't change. mass does not affect velocity. |
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P=E/t
power= energy divided by time |
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| If given an objects constant velocity, and a constant force, how can power be equated? |
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