Reading Quiz. 1. Which is true? The gravitational force between two particles ___ 1. can be shielded by the presence of an intervening mass. ___ 2. is inversely proportional to the distance between the particles. ___ 3. obeys the law of superposition.
1. Which is true? The gravitational force between two particles
___ 1. can be shielded by the presence of an intervening mass.
___ 2. is inversely proportional to the distance between the particles.
___ 3. obeys the law of superposition.
___ 4. is independent of the distance between the particles.
___ 1. equal to g at the surface of Earth.
___ 2. different on the Moon than on Earth.
___ 3. obtained by measuring the speed of
falling objects having different masses.
___ 4. none of the above
___ 1. The gravitational attraction of Earth and the Sun provides a centripetal
acceleration explaining Earth’s orbit.
___ 2. The gravitational and inertial masses of an object are equivalent.
___ 3. The radial line segment from the Sun to a planet sweeps out equal areas in equal time intervals.
___ 1. escape velocity
___ 2. perihelion
___ 3. gravitational mass
___ 4. Hubble’s constant
1) The game of tetherball is played with a ball tied to a pole with a string. When the ball is struck, it whirls around the pole as shown. At this moment, in what direction is the acceleration of the ball, and what causes the acceleration?
____ a) up ____ a) gravity
____ b) down ____ b) gravity
____ c) right ____ c) string
____ d) left ____ d) string
____ e) not accelerated ____ e) not needed
____ a) left
____ b) right
____ c) up
____ d) forward
____ e) backward
____ a) northward, projectile motion
____ b) southward, projectile motion
____ c) eastward, projectile motion
____ d) westward, projectile motion
____ e) south-east, projectile motion
____ f) north-east, projectile motion
____ a) It is moving in a straight line.
____ b) It is moving in a circle.
____ c) It is moving in a parabola.
____d) None of the above is definitely true all of the time.
1) A flat puck (mass M) is rotated in a circle on a frictionless air hockey tabletop, and is held in this orbit by a light cord which is connected to a dangling mass (mass m) through the central hole as shown in the figure below. Find the speed of the puck in terms of the given quantities.
2) At what minimum speed must a roller coaster be traveling when upside down at the top of a circle if the passengers are not to fall out? Assume the radius of curvature is 8.6 m.
1) If the bank of a road is designed for a speed of 50 mph, how does the car tend to slip at a speed of 60 mph?
____ a) not at all
____ b) inwards towards the center of curvature
____ c) outwards away from the center
What (if anything) prevents this from happening?
____ a) radially outward
____ b) radially inward
____ c) straight towards the earth
____ d) it is impossible to produce artificial gravity
____ a) the denser one
____ b) the less dense one
____ c) they both reach at the same time
____ d) they do not move
1) For a car traveling with speed v around a curve of radius r, determine a formula for the angle at which a road should be banked so that no friction is required.
Where is the gravitational attraction of the earth greatest?
____ a) at the Poles
____ b) at the equator
____ c) same all over the earth
1) Calculate the acceleration due to gravity on the moon. The moon’s radius is about 1.74 x 106 m and its mass is 7.35 x 1022 kg.
2) Determine the mass of the sun. Take the distance from the sun to be 1.5 x 1011 m.
3) A geo-synchronous satellite is one that stays above the same point on the equator of the earth. Such satellites are used for purposes as cable TV transmission, for weather forecasting, and as communication relays. What is the height above the earth’s surface such a satellite must orbit? Do lower orbit satellites move faster or slower?
1) According to Kepler’s third law, the time needed for a planet to go around the sun
____ a) depends on its mass
____ b) depends on the average radius of orbit
____ c) depends on its speed of rotation
____ d) is the same for all the planets
____ a) is constant
____ b) is highest when it is closest to the sun
____ c) is lowest when it is closest to the sun
____ d) varies, but not with respect to its distance from the sun
____ a) satellite 1 and satellite 1
____ b) satellite 1 and satellite 2
____ c) satellite 2 and satellite 1
____ d) satellite 2 and satellite 2
____ e) they have the same period and speed