Physics: Circular Motion and Gravitation Flashcards
What is centripetal acceleration?
The acceleration directed toward the center of a circular path
What is the equation for centripetal acceleration?
a=tv^2/r
centripetal acceleration = (tangential speed)^2/radius of circular path
A rope attaches a tire to an overhanging tree limb. A girl swinging on the tire has a centripetal acceleration of 3.0 m/s^2. If the length of rope is 2.1 m, what is the girl’s tangential speed?
2.5 m/s
As a young boy swings a yo-yo parallel to the ground and above his head, the yo-yo has a centripetal acceleration of 250 m/s^2. If the yo-yo’s string is 0.50 m long, what is the yo-yo’s tangential speed?
11.18 m/s
A dog sits 1.5 m from the center of a merry-go-round. The merry-go-round is set in motion, and the dog’s tangential speed is 1.5 m/s. What is the dog’s centripetal acceleration?
1.5 m/s^2
A racecar moving along a circular track has a centripetal acceleration of 15.4 m/s^2. If the car has a tangential speed of 30.0 m/s, what is the distance between the car and the center of the track?
58.4 m
What is the equation for centripetal force?
F = m x v^2/r
Centripetal force = mass x (tangential speed)^2/radius of circular path = mass x centripetal acceleration
A 2.10 m rope attaches a tire to an overhanging limb. A girl swinging on the tire has a tangential speed of 2.5 m/s. If the magnitude of the centripetal force is 88.0 N, what is the girl’s mass?
29.6 kg
A bicyclist is riding at a tangential speed of 13.2 m/s around a circular track.the magnitude of the centripetal force is 377 N, and the combined mass of the bicycle and rider is 86.5 kg. What is the track’s radius?
40.0 m
A dog sits 1.50 m from the center of a merry-go-round and revolves at a tangential speed of 1.80 m/s. If the dog’s mass is 18.5 kg, what is the magnitude of the centripetal force on the dog?
39.96 N
A 905 kg car travels around a circular track with a radius of 3.25 km. If the magnitude of the centripetal force is 2140 N, what is the car’s speed?
35 m/s
What is Newton’s Law of Universal Gravitation?
Fg = G x ((m1 x m2)/r^2)
Gravitational force = gravitational constant x (mass 1 x mass 2/distance between masses^2)
What is the gravitational constant?
6.673x10^-11 (N x m^2)/kg^2
Where is gravity measured from?
The center of each mass
What must the distance between two 0.800 kg balls be if the magnitude of the gravitational force is 8.92x10^-11?
0.69 m
Who set out to discover Earth’s density, and paved the way to discover G?
Henry Cavendish
How fast does gravity travel?
The speed of light
What is Kepler’s First Law of Planetary Motion?
Each planet travels in an elliptical orbit around the sun, and the sun is at one of the focal points.
What is Kepler’s Second Law of Planetary Motion?
An imaginary line drawn from the sun to any planet sweeps out equal areas in equal time intervals
What is Kepler’s Third Law of Planetary Motion?
The square of a planet’s orbital period (T^2) is proportional to the cube of the average distance (r^3) between the planet and the sun
What is the equation for orbital period?
Orbital period = 2 pi x square root ((mean radius^3)/(gravitationalconstant)(mass of central object))
What is the equation for orbital speed?
Orbital speed = square root ((gravitational constant)(mass of central object/mean radius))
Suppose you know the mean distance between Mercury and the sun and Venus and the sun. You also know the period of Venus’s orbit around the sun. Can you find the period of Mercury’s orbit, and if so, how?
Yes, using Kepler’s Third Law of Planetary Motion.
T1^2/T2^2 = r1^3/r2^3
What is torque?
A quantity that measures the ability of a force to rotate an object around its axis
What is the equation for torque?
tau = Fd sin theta torque = force x lever arm
What is a lever arm?
the perpendicular distance from the axis of rotation to a line drawn along the direction of the force
Find the magnitude of the torque produced by a 3.0 N force applied to a door at a perpendicular distance of 0.25 m from the hinge.
O.75 Nxm
If the torque required to loosen a nut on the wheel of a car has a magnitude of 40 Nxm, what minimum force must be exerted by a mechanic at the end of a 30.0 cm wrench to loosen the nut?
133 N
What are the six simple machines?
Lever, wedge, inclined plane, wheel and axle, pulley, and screw
What are the three simplest simple machines
Lever, inclined plane, wheel and axle (The screw is a mixture of a wheel and axle and an inclined plane, the wedge is two inclined planes stuck together, and pulleys are sets of wheels and axles)
What is equation for mechanical advantage?
force out/force in
