Deck 5: Gravity

Question 1

Newtonian physics tells us that Kepler's second law

A) is a result of the conservation of angular momentum.
B) is a result of the conservation of energy.
C) is a result of the conservation of mass.
D) is a consequence of the inverse square law.
E) is incorrect and needs to be modified.

Answer 1

is a result of the conservation of angular momentum.

Question 2

The diagram below illustrates the orbit of a satellite around Earth.Which letter indicates the location of perigee?

A) A
B) B
C) C
D) D
E) Perigee is the time to complete an orbit.

Answer 2

C

Question 3

The circular velocity of a satellite orbiting Earth is given by .In this equation,

A) M represents the mass of the satellite,and r is its radius.
B) M represents the mass of Earth and r the radius of Earth.
C) M represents the mass of the satellite and r the distance from Earth to the satellite.
D) M represents the mass of Earth and r the distance from Earth to the satellite.
E) M represents the mass of the satellite and r the distance from Earth's surface to the satellite.

Answer 3

M represents the mass of Earth and r the distance from Earth to the satellite.

Question 4

The radius of Earth is 6378 km.The force of gravity on a 1 kg ball at Earth's surface is 9.8 kg m s ^{- 2}.What is the force of gravity on this same ball when the ball is located 12,756 km from Earth's center? G = 6.67*10 ^{- 11} N m² kg ^{- 2}

A) 2.45 kg m s ^{- 2}
B) 39.2 kg m s ^{- 2}
C) 4.9 kg m s ^{- 2}
D) 19.6 kg m s ^{- 2}
E) 9.8 kg m s ^{- 2}

Question 5

Gravity obeys the inverse square law.This statement implies that the gravitational force of one body on another will be ____ apart.

A) two times stronger at 2 meters than at 6 meters
B) three times stronger at 2 meters than at 6 meters
C) six times weaker at 2 meters than at 6 meters
D) nine times stronger at 2 meters than at 6 meters
E) The brightness of the force will not change with distance between the two bodies.

Question 6

According to Galileo (and not according to Aristotle),an object with no forces (and no friction)on it will

A) move faster and faster.
B) stop moving eventually.
C) move at a constant speed forever.

Question 7

If the orbital velocity of the moon is 1.0 km/s,what is the orbital velocity of a satellite that is 1/16th as far from Earth as the moon? Hint: There is a long way and a short way to do this calculation. G = 6.67* ^{- 11} N m² kg ^{- 2} and

A) 1/16 km/s
B) 16 km/s
C) 8 km/s
D) 1/8 km/s
E) 4 km/s

Question 8

A(n)____ orbit is one where the orbiting object is always above the same location on Earth's surface.

A) elliptical
B) geosynchronous
C) closed
D) hyperbolic
E) parabolic

Question 9

The ____ of an object is a measure of the amount of matter it contains.On the other hand ____ is a measure of the gravitational force on an object.

A) weight,mass
B) mass,weight
C) energy,force
D) force,energy
E) momentum,energy

Question 10

When we say that gravitation is universal we mean that

A) objects with no forces on them move with constant speed.
B) an object with a force on it accelerates in the direction of the force.
C) it is a property of all matter in the universe.
D) the force of gravity from one object extends to infinity.
E) both answers c and d

Question 11

A comet near the sun whose orbit is ____ would never be near the sun again.

A) elliptical
B) circular
C) hyperbolic
D) apogee
E) following an inverse square law

Question 12

The apogee of a(n)____ orbit does not exist.

A) elliptical
B) closed
C) parabolic
D) geosynchronous
E) All orbits have both a perigee and an apogee.

Question 13

Galileo found that

A) falling objects fall at a constant speed.
B) heavy and light objects fall at the same rate.
C) heavy objects fall faster than lighter objects.
D) the moon's orbit is elliptical.
E) only objects made of earth and water fell to the ground.

Question 14

When two objects of unequal mass orbit each other,the center of mass is

A) at the center of the more massive object.
B) at the center of the least massive object.
C) half way between the centers of each object.
D) always closer to the less massive of the two objects.
E) always closer to the more massive of the two objects.

Question 15

According to Galileo,the acceleration of a freely falling object due to gravity is ____ the larger the mass of the object.

A) larger
B) smaller
C) always the same

Question 16

According to Aristotle an object with no forces in it will

A) move faster and faster.
B) stop moving eventually.
C) move at a constant speed forever.

Question 17

Perigee is

A) the point in the moon's orbit when the moon is farthest from Earth.
B) the point in a planet's orbit when the planet is farthest from the sun.
C) the point in an object's orbit around Earth,when the object is closest to Earth.
D) the point in a planet's orbit when the planet is closest to the sun.
E) the time it takes a celestial object to complete one orbit around the object it is orbiting.

Question 18

According to Aristotle,which of the following would be an example of violent motion?

A) an apple falling from a tree
B) a person pushing a car along the street
C) an arrow moving through the air after leaving the bow
D) warm air rising above hot pavement
E) a barrel rolling down a ramp

Question 19

Newton concluded that some force had to act on the moon because

A) a force is needed to keep the moon in motion.
B) a force is needed to pull the moon outward.
C) a force is needed to pull the moon away from straight-line motion.
D) the moon moved at a constant velocity.
E) all of the above

Question 20

Which of the following is NOT an example of conservation of angular momentum?

A) A diver slowing his somersault by moving from a tuck,or curled,position to a layout,or open,position.
B) A skater speeding up a spin by pulling her arms and legs closer to her body.
C) An artificial satellite moving faster at perigee than at apogee.
D) A basketball that spins slower and slower as it spins on your finger.
E) A man spinning on a stool and extending weights outward from his body and then pulling them in again.

Question 21

The equivalence principle can be illustrated by

A) a person riding in an elevator.
B) a space capsule coasting through space at constant velocity.
C) the change in mass of a moving body.
D) the formation of energy by nuclear fusion.
E) the increase in the speed of light from a star as the light moves past the sun during a solar eclipse.

Question 22

How much energy is released if 2 kg of matter is converted into pure energy? Hint: E = mc² and c = 3.0*10⁸ m/sec

A) 2 joules
B) 6*10⁸ joules
C) 1.2*10⁹ joules
D) 9*10¹⁶ joules
E) 1.8*10¹⁷ joules

Question 23

Since gravity behaves as an inverse square relation the force due to gravity between two masses

A) will increase as the distance between the two masses increases.
B) will decrease as the square of the distance between the two masses increases.
C) will cause the two masses to move away from each other.
D) will cause the two masses to move in a straight line.
E) will cause the two masses to orbit each other.

Question 24

If a theory is believed with great confidence because it has been thoroughly tested then it will be called a

A) hypothesis.
B) natural law.
C) prediction.
D) corollary.

Question 25

Which type of curve would accurately represent a closed orbit?

A) ellipse
B) hyperbola
C) parabola
D) straight line

Question 26

The second postulate of special relativity states that

A) observers cannot detect their uniform motion except relative to other objects.
B) observers cannot distinguish locally between inertial forces due to acceleration and uniform gravitational forces due to the presence of a massive body.
C) the laws of physics are the same for all observers,no matter what their motion,as long as they are not accelerating.
D) the speed of light is constant and will be the same for all observers independent of their motion relative to the light source.
E) the acceleration of an object is proportional to the applied force and inversely proportional to its mass.

Question 27

Tides occur because the gravitational force of the moon on the Earth ____ with increasing distance from the moon.

A) stays constant
B) increases
C) decreases

Question 28

Tides occur

A) at new moon and first quarter moon.
B) at first quarter and third quarter moons.
C) at new moon and full moon.
D) at third quarter and full moons.
E) at noon and midnight.

Question 29

____ occur when the moon is new and the moon is full.

A) Neap tides
B) Spring tides
C) Total solar eclipses
D) Annular eclipses
E) A coppery red moon will

Question 30

Newton's law of gravitational force is expressed as follows ...

A) An object with no force on it moves in a straight line with constant velocity.
B) An object with a force on it is accelerated in the direction of the force an amount inversely proportional to its mass and directly proportional to the size of the force.
C) For every action there is an equal and opposite reaction.
D) The force between two objects is directly proportional to the product of their masses and inversely proportional to the distance between them squared.

Question 31

According to the theory of general relativity,gravity is caused by

A) the equivalence principle.
B) the change in mass of a moving body.
C) the curvature of space-time.
D) the constant speed of light.
E) none of the above.

Question 32

If the mass of the Earth decreased by a factor of two with no change in radius,your weight would

A) increase by a factor of 4.
B) increase by a factor of 2.
C) stay the same.
D) decrease by a factor of 2
E) decrease by a factor of 4.

Question 33

Due to the curvature of space-time by the sun,light from stars that passes near the edge of the sun will

A) be bent so that the stars appear further from the edge of the sun than if space-time was not curved.
B) be bent so that the stars appear closer to the edge of the sun than if space-time was not curved.
C) be bent so that the stars are no longer visible.
D) not be affected by the curvature of space-time.

Question 34

Spring tides occur

A) at new moon and first quarter moon.
B) at first quarter and third quarter moons.
C) at new moon and full moon.
D) at third quarter and full moons.
E) at noon and midnight.

Question 35

What is the circular velocity of an object orbiting Earth at a distance of 100,000 km from Earth's center? G = 6.67*10^-11 N m² kg^-2

A) 2 m/s
B) 20 m/s
C) 200 m/s
D) 2000 m/s
E) 20,000 m/s

Question 36

The force due to gravity between two objects depends on

A) I & II
B) I & III
C) II & IV
D) I,II,& III
E) I,II,III,& IV

Question 37

One of the first tests of the general theory of relativity was

A) the description of the orbit of the moon.
B) the determination of the speed of light to be constant.
C) the change in mass of a particle moving at a high speed.
D) the demonstration of a hammer and a feather falling at the same rate on the moon.
E) the determination of the rate of advance of the perihelion of Mercury's orbit.

Question 38

The ____ produce(s)tides on the Earth.

A) moon alone
B) sun alone
C) both moon and sun

Question 39

How often do spring tides occur?

A) Twice a day
B) Twice a week
C) Twice a month
D) Twice a year

Question 40

What is the escape velocity from the moon for a lunar landing module sitting on the moon's surface? Hints: V_e= square root of (2GM/r); the mass of the moon is 7.2*10²² kg; its radius is 1738 km; G = 6.67*10 ^{- 11} N m² kg ^{- 2}

A) 2.3 m/s
B) 23 m/s
C) 2.3 km/s
D) 23 km/s
E) 11 km/s

Question 41

The ____________________ of a particle is the mass we would measure if the particle were not moving.

Question 42

The neap tides can only occur when the Moon's position is at or near one of its orbital nodes.

Question 43

The spring tides occur during the new and full lunar phases.

Question 44

Newton's first law of motion was very similar to descriptions of motion given by ____________________.

Question 45

Changing the direction of a moving body does not change its velocity.

Question 46

The escape velocity at a given distance from a planet is less than the circular velocity of an orbit around that planet at the same distance.

Question 47

Galileo developed three theories of motion that became laws of motion when Newton proved Galileo's theories correct.

Question 48

Using the law of gravity and the three laws of motion,Newton showed that the mass of a planet (like Jupiter)could be calculated from ...

A) the distance of a satellite from Jupiter
B) how long it takes the satellite to orbit Jupiter once
C) a & b
D) none of the above

Question 49

Aristotle believed that objects falling to the ground fell at a constant speed.

Question 50

Galileo believed that motion stopped in the absence of a force.

Question 51

The ____________________ of the moon's orbit is the place where it is farthest from Earth.

Question 52

The law of gravitation is termed universal because it is a property of all material objects.

Question 53

Ocean tides of low amplitude that occur at first and third quarter moons are called ____________________.

Question 54

The apparent positions of stars around the sun during an eclipse have been used to prove the general theory of relativity.

Question 55

Newton's first law of motion is expressed as follows ...

A) An object with no force on it moves in a straight line with constant velocity.
B) An object with a force on it is accelerated in the direction of the force an amount inversely proportional to its mass and directly proportional to the size of the force.
C) For every action there is an equal and opposite reaction.
D) The force between two objects is directly proportional to the product of their masses and inversely proportional to the distance between them squared.

Question 56

Aristotle believed that motion continued in the absence of a force.

Question 57

The force due to gravity has the mathematical form: .

Question 58

The lunar tides on Earth are making the moon recede from Earth.

Question 59

Edmund Halley found that the comet named after him moved in a(n)____________ orbit around the sun once per 75 years under the gravitation of the sun.

A) cubical
B) square
C) elliptical

Question 60

The ____________________ states that an observer cannot distinguish locally the difference between inertial forces due to acceleration and uniform gravitational forces due to the presence of a massive object.

Question 61

Once a theory has been tested thoroughly and is confidently believed by scientists it becomes a ____________________.