# Shared Flashcard Set

## Details

Physics - Mechanics
MCATs
46
Physics
07/09/2012

Term
 Newton's first law
Definition
 objects at rest, stay at rest and objects in motion will contiue with constant velocity.   no net force = no acc.
Term
 Newton's second law
Definition
 Fnet=ma when Fnet=0, object not acc, but could still be moving
Term
 Newton's 3rd law
Definition
 F1-on-2=F2-on-1
Term
 force of grav eq.   force of grav on incline eq.
Definition
 Fg=mg=w   Fg= mgsinθ -parallel to horitontal Fg = mg cosθ - perp to horiztontal
Term
 law of gravitation eq.
Definition
 Fgrav= G(Mm/r2)   G=grav constant: 6.7 x10-11 N.m2/kg2
Term
 Normal force eq.
Definition
 FN= mg
Term
 for kinetic friction, its magnitiude is proportional to what?
Definition
 the magnitude of the normal force
Term
 Force of kentic friction eq.
Definition
 Ff = μkFN   *only magnitude based
Term
 max force of static friction eq.
Definition
 Ffmax=μsFN
Term
 centripital foce eq
Definition
 Fc=mac=mv2/r
Term
 cosθ sinθ values
Definition
 [image]
Term
 Center of Mass for Point Masses
Definition
 xCM=m1x1 + m2x2..../m1 + m2....
Term
 Center of grav eq.
Definition
 xCG = w1x1 +w2x2..../w1 + w2
Term
 an object moving in a circular path executes uniform circular motion if what is occuring to it's speed?
Definition
 if its speed is constant
Term
 centripetal acc. eq.
Definition
 ac=v2/r
Term
 Torque eq.
Definition
 T=rFsinθ=lF   l - lever arm r- distance between pivot point and force of application
Term
 Work by a constant Force across a horizontal plane. at an angle.
Definition
 W = Fdcosθ   θ - angle between F and d   W in Joules (J)
Term
 Power eq. in realtion to work
Definition
 P = W/t   work over time P in Watts (W)
Term
 kinetic energy
Definition
 KE = 1/2mv2   KE in joules (J)
Term
 Work energy theorem
Definition
 Wtotal = ΔKE
Term
 equation for power expended by air resistance on a falling object
Definition
 P = Fv = -mgv   v-velocity  neg sign because force is opposite direction of velocity
Term
 Which has the higher value? The work done by gravity on a falling object, or the work done by air resistance?
Definition
 work done by gravity. because: Wbygrav=mgh while work done by air resistance is negative, since it works in the obosite direction of velocity.
Term
 equation for gravitational potential energy and it's unit of measure
Definition
 PEgrav = mgh in joules (J)
Term
 Why is air resistance ignored when a compact object falls a very short distance?
Definition
 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.
Term
 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?
Definition
 [image]
Term
 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?
Definition
 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.
Term
 What causes an object to experience an artificial gravitational acceleration in a rotating space station?
Definition
 The object's propenstiy to move in a striaght line while the space station forces it onto a curved path.
Term
 The work done by a force that acts over a displacement is given by the equation:
Definition
 W=Fd
Term
 relationship between work and kinetic energy (eq)
Definition
 w = ΔKE
Term
 equation for determining power when energy expended is given.
Definition
 P = E/t    power = energy/time
Term
 give the equivalent of a watt using kg, m, and secs.
Definition
 watt = joule/s = kg.m2/s3
Term
 if given an object's constant velocity and the constant force necessary to acheive this, which equation would you use to calculate power?
Definition
 P=Fv
Term
 what unit is power in?
Definition
 watts
Term
 If an object is moving with a constant velocity of 5 m/s, what is the power needed to maintain motion?
Definition
 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.
Term
 equation for total momentum before and after collision if items stick together
Definition
 p=p' mAvA + mBvB= (m+m)v'   momentum before = moment after
Term
 is sinΘ or cosΘ used when the angle is perp or parallel to horazontal?
Definition
 perp = cosΘ parallel = sinΘ
Term
 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?
Definition
 mAvA = mBvB vA/vB = mA/mB
Term
 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?
Definition
 800J. machines don't reduce the amount of work required. the work done is a fixed rate.
Term
 conservation of energy equation
Definition
 Ei = Ef KEi + PEi = KEf + PEf
Term
 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?
Definition
 momentum will be conserved, but kinetic energy would not.
Term
 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?
Definition
 [image]
Term
 how much gravitaional energy is lost when a 10kg object is droped and reaches a speed of 30 m/s?
Definition
 4500J. because -PE=KE,  KE=1/2mv2. solve.
Term
 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)
Definition
 it won't change. mass does not affect velocity.
Term
 cosΘ and sinΘ values
Definition
 [image]
Term
 equation for power
Definition
 P=E/t   power= energy divided by time
Term
 If given an objects constant velocity, and a constant force, how can power be equated?
Definition
 P=Fv
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