Chapter 6: Uniform Circular Motion and Gravitation Flashcards
Define angular velocity
the rate of change of the angle with which an object moves on a circular path
Symbol: ω
Define arc length
Δs, the distance traveled by an object along a circular path
Define banked curve
the curve in a road that is sloping in a manner that helps a vehicle negotiate the curve
Define center of mass (com)
the point where the entire mass of an object or of a system of objects can be thought to be concentrated
Define centrifugal force
a fictitious force that tends to throw an object off when the object is rotating in a non-inertial frame of reference
Define centripetal acceleration
the acceleration of an object moving in a circle, directed toward the center
Define centripetal force
any net force causing uniform circular motion
Define coriolis force
the fictitious force causing the apparent deflection of moving objects when viewed in a rotating frame of reference
Define fictitious force
a force having no physical origin
Define gravitational constant, G
a proportionality factor used in the equation for Newton’s universal law of gravitation; it is a universal constant—that is, it is thought to be the same everywhere in the universe
Define ideal angle
the angle at which a car can turn safely on a steep curve, which is in proportion to the ideal speed
Define ideal banking
the sloping of a curve in a road, where the angle of the slope allows the vehicle to negotiate the curve at a certain speed without the aid of friction between the tires and the road; the net external force on the vehicle equals the horizontal centripetal force in the absence of friction
Define ideal speed
the maximum safe speed at which a vehicle can turn on a curve without the aid of friction between the tire and the road
Define microgravity
an environment in which the apparent net acceleration of a body is small compared with that produced by Earth at its surface
define Newton’s Universal law of gravitation
every particle in the universe attracts every other particle with a force along a line joining them; the force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
Define non-inertial frame of reference
an accelerated frame of reference
Define radians
A unit of angle measurement
Define radius of curvature
Radius of a circular path
Define rotation angle in words
the ratio of the arc length to the radius of curvature on a circular path
What is the rotation angle equation?
Δθ=Δs/r
Δθ = change in angle
Δs = change in arc length
r = radius
Define ultracentrifuge
a centrifuge optimized for spinning a rotor at very high speeds
Define uniform circular motion.
the motion of an object in a circular path at a constant speed
A pilot can withstand an acceleration of up to 9g, about 88m/s^2 before blacking out. What is the acceleration experience by a pilot flying in a circle of constant radius at a constant speed of 525 m/s if the radius is 2820 m?
98 m/s^2 (yes the pilot blacks out)
Explanation:
I. Assess what you have: radius, and velocity
II. Asses what you need: Centripetal acceleration
III. Find a fitting equation: a_c = v^2 / r
IV: Plug in the numbers: a_c = 525m/s^2 / 2820 m
V. Solve: 98m/s^2
What is the equation for centripetal acceleration?
a_c = v^2 / r
a_c = centripetal acceleration (using _ to represent subscript)
v = velocity
r= radius
Hai swings a ball in a verticle circle as the end of a strong that always remains taut.
At the top of the circle, the centripetal force on the ball is…
A. one-half its weight
B. Twice its weight
C. smaller than its weight
D. larger than its weight
E. equal to its weight
D. larger than its weight
Explanation: The centripetal force is larger than the weight at the top of the circle because the weight and the tension forces both point toward the center of the circle
Sandra is on a rotating Ferris wheel.
When Sandra is at the bottom of the Ferris wheel’s rotation, how does the magnitude of the normal force N exerted on her by her seat compare to her weight mg?
A. N = 2mg
B. N = mg
C. N < mg
D. N > mg
E. N = 1/2 mg
D. N > mg
Explanation: The normal force must be larger than the wight in order for there to be a centripetal force
According to Newton’s Law of universal gravitation F = G (m1m2/r^2)
If both masses are doubled, the force is…
Four times as much as the original
According to Newton’s Law of universal gravitation F = G (m1m2/r^2
If the radius is doubled, the force is…
One-forth of the original value
