Chapter 2 - Forces, Circular Motion, and Gravitation Flashcards
Mechanical advantage of an inclined plane
1/sinθ
Equation: angular acceleration given tangential acceleration
α = a/r
a = tangential acceleration
How many degrees is 1 radian?
57.3º
Equation: mechanical advantage
Mechanical advantage = weight of object supported/applied forced needed to support the object
Equation: angular velocity, given period
ω = 2π/T
Equation: Newton’s law of gravitation (Force) or Inverse Square Law
F = GM1M2/r2
In what direction does centripetal acceleration point?
toward the center of a circle, perpendicular to the velocity
Equation: centripetal force, given tangential velocity
Fc = m(v2/r)
Kepler’s third law
Orbital period squared is equal to radius cubed.
Which is greater: kinetic or static friction?
static friction
As radius changes, does ω or v change?
V changes.
Tangential velocity increases as the radius increases, because you have to move farther to complete one revolution.
Equation: Normal force on inclined plane
N = mgcosθ
What is the equal and opposite force to centripetal force?
centrifugal force
Equation: angle in degrees, given radians
θº = θradians (180º/π)
Newton’s first law of motion
An object at rest remains at rest. An object in motion will continue to move with uniform velocity in a straight line, unless acted upon by an external force.
Equation: angle in radians, given degrees
θradians = θº (π/180º)
Equation: Newton’s second law (Net Force)
F = ma
As the radius decreases, how does centripetal acceleration change?
Ac decreases, because tangential velocity decreases.
Equation: circumference of a circle
2πr
Kepler’s first law
All orbital paths are elliptical.
Equation: friction
friction = µs/kN
µ = coefficient of friction
N = normal force
Equation: centripetal acceleration, given angular velocity
ac = ω2r
What does an acceleration of so many g’s mean?
an acceleration of so many times the force of gravity
Units of Newtons (N)
N = kg(m/s2)
Mechanical advantage of a pulley is equal to what?
the number of vertical ropes (tensions) supporting the pulley
How many radians make up a circle?
2π radians
Equation: Kepler’s third law
T2 = (4π2/GM)R3
M = mass of orbited object
Equation: Acceleration down an inclined plane
a = gsinθ
Newton’s second law of motion
A force acting on an object will give that object an acceleration in the direction of the force. The acceleration of the object is directly proportional to the resultant force applied and inversely proportional to the mass of the object.
Newton’s third law of motion
If one object exerts a force on a second object, the second object will exert a reactive force on the first object of equal magnitude, in the opposite direction.
Kepler’s second law
An orbiting object moves faster and is subject to a greater force when it is closer to the object about which it orbits.
Equation: centripetal acceleration, given tangential velocity
ac = v2/r
Equation: Weight
W = mg
Equation: angular velocity
ω = v/r
v = tangential velocity
Equation: time to complete revolution (Period), given frequency
T = 1/f
