Conceptual Physics Ch 9

neutron star

star that has undergone a gravitational collapse in which electrons are compressed into protons to form neutrons.

universal gravitational constant

the proportionality constant G that measures the strength of gravity in the equation for Newton's law of universal gravitation.

The concept of force is not fundamental to A) Newton's theory of gravitation. B) Einstein's theory of gravitation. C) both of these D) neither of these

B) Einstein's theory of gravitation.

When the elevator cable breaks, the elevator falls freely, so your weight reading is A) greater. B) less. C) zero. D) the normal weight.

C) zero.

Einstein's Theory of Gravitation

Gravitational field is a warping of space-time by a planet

Mass of Earth

6.67E x 10^24 kg

A person weighs 150 pounds. He steps in an elevator and stands on a scale. If the elevator is moving upwards with a constant speed, what is the reading of the scale? A) 150 pounds. B) Less than 150 pounds. C) Greater than 150 pounds.

A) 150 pounds.

How far must one travel to get away from the Earth's gravitational field? A) Forget it; you can't travel far enough. B) to a region well beyond the moon C) to a region beyond the solar system D) to a region above the Earth's atmosphere

A) Forget it; you can't travel far enough.

Suppose you weigh 400 pounds and want to weigh only 100 pounds. Instead of going on a diet, you could live in space. How far from the center of the Earth would you have to live? A) The distance would be two Earth radii away from the center of the Earth. B) The distance would be three Earth radii away from the center of the Earth. C) The distance would be four Earth radii away from the center of the Earth.

A) The distance would be two Earth radii away from the center of the Earth.

The Earth's gravitational field extends A) both inside and outside the Earth and throughout the entire universe. B) neither of these C) only above and beyond the Earth's surface and cancels inside the Earth

A) both inside and outside the Earth and throughout the entire universe.

If the mass of one planet is somehow doubled, the force of gravity between it and a neighboring planet A) doubles. B) quadruples C) reduces by half. D) reduces by one-quarter.

A) doubles.

Newton's most celebrated synthesis was and is of A) earthly and heavenly laws. B) weight on Earth and weightlessness in outer space. C) masses and distances. D) the paths of tossed rocks and the paths of satellites

A) earthly and heavenly laws.

When an elevator accelerates upward, your weight reading on a scale is A) greater. B) less. C) zero. D) the normal weight.

A) greater.

A 150 pound astronaut is inside the space shuttle, orbiting around the Earth just above the Earth's atmosphere (the atmosphere's thickness is very small compared to the radius of the Earth). The force of gravity acting on the astronaut A) is roughly 150 pounds. B) Around 120 pounds C) 0 pounds.

A) is roughly 150 pounds.

The force of gravity between two planets depends on their A) masses and distance apart. B) planetary atmospheres. C) rotational motions. D) All of the above.

A) masses and distance apart.

The reason the moon does not crash into the Earth is that the A) moon has a sufficient tangential speed to keep it in orbit for a very long time. B) moon has less mass than the Earth. C) gravitational pull of other planets keeps the moon up. D) none of these E) Earth's gravitational field is weak at the moon.

A) moon has a sufficient tangential speed to keep it in orbit for a very long time.

The best time for digging clams (when the low tide is extra low) is during the time of the A) new or full moon. B) half moon. C) quarter moon. D) none of these times in particular

A) new or full moon.

Newton discovered A) that gravity is universal. B) neither C) gravity.

A) that gravity is universal.

The universal gravitational constant, G, which links force to mass and distance, is similar to the familiar constant A.) pie B) g. C) acceleration due to gravity. D) speed of uniform motion.

A.) pie

Wormhole

An enormous distortion of space-time

When an elevator accelerates downward, your weight reading is A) greater. B) less. C) zero. D) the normal weight.

B) less.

If the masses of two planets are each somehow doubled, the force of gravity between them A) doubles. B) quadruples. C) reduces by half. D) reduces by one-quarter.

B) quadruples.

A person weighs 150 pounds. He is standing on a scale in an elevator and stands on a scale. The elevator is accelerating upwards at a rate of 10 m/s/s, what is the reading of the scale? A) 150 pounds B) roughly 300 pounds C) 75 pounds

B) roughly 300 pounds

An asteroid exerts a 360-N gravitational force on a nearby spacecraft. This force is directed A) away from the asteroid. B) toward the asteroid. C) toward the sun.

B) toward the asteroid.

A person weighs 150 pounds. He is standing on a scale inside an elevator. If the elevator is free-falling downward (perhaps the cable broke), what is the reading of the scale? A) roughly 25 pounds B) 150 pounds C) 0 pounds

C) 0 pounds

A 150 pound person decides to move to the center of the Earth (carving out a little cavity for her house). What is the net force of gravity exerted by the Earth on this person? B) Much less than 150 pounds but greater than zero. B) 150 pounds C) 0 pounds.

C) 0 pounds.

If you weigh yourself in an elevator, you'll weigh more when the elevator A) moves upward. B) moves downward. C) accelerates upward. D) All of the above.

C) accelerates upward.

According to Newton, doubling the distance between two interacting objects A) multiplies by 2 the gravitational force between them. B) divides by 2 the gravitational force between them. C) divides by 4 the gravitational force between them. D) multiplies by 4 the gravitational force between them.

C) divides by 4 the gravitational force between them.

If the mass of the Earth somehow increased with no change in radius, your weight would A) stay the same. B) decrease. C) increase also.

C) increase also.

When a star collapses to form a black hole, its mass A) decreases. B) increases. C) remains the same.

C) remains the same.

Suppose a rocket ship, while sitting on Earth, has a weight of 10,000 N. The rocket ship takes off and reaches a distance from Earth's center of 3R Earth. What is the force due to gravity acting on the spaceship? A) 10,000 N B) roughly 3,333 N C) roughly 1,100 N

C) roughly 1,100 N

What would happen to Earth if the Sun became a black hole? A.) It would break away from the attraction of the Sun. B) It would be pulled into the Sun. C) It would become a black hole too. D) None of the above.

D) None of the above.

Universal gravitation

Everything attracts everything else

Universal Gravitational Constant, G

F = G (m1 x m2 /distance) G = 6.67E x 10^-11 Nm2/kg2

Universal Law of Gravity

Force ~ mass1 x mass2 / distance

CG

abbreviation for center of gravity

gravitation

attraction between objects due to mass.

black hole

concentration of mass resulting from gravitational collapse, near which gravity is so intense that not even light can escape.

weightlessness

condition of free fall toward or around Earth in which an object experiences no support force (and exerts no force on a scale).

perturbation

deviation of an orbiting object (e.g. a planet) from its path around a center of force (e.g. the Sun) caused by the action of an additional center of force (e.g. another planet).

law of universal gravitation

for any pair of objects, each particle attracts the other object with a force that is directly proportional to the product of the masses of the objects, and inversely proportional to the square of the distance between them (or their centers of mass if spherical objects), where F is the force, m is the mass, d is the distance, and G is the gravitation constant.

gravitational field

force that exits in the space around every mass or group of masses; measured in newtons per kilogram.

spring tide

high or low tide that occurs when the Sun, Earth and Moon are all lined up so that the tides due to the Sun and Moon coincide, making the high tides higher than average and the low tides lower than avaerage.

A person weighs 150 pounds. He is standing on a scale inside an elevator. The elevator is moving downward and slowing down (coming to a stop). What is the reading of the scale? A) Less than 150 pounds. B) 150 pounds C) higher than 150 pounds

higher than 150 pounds

wormhole

hypothetical enormous distortion of space and time, similar to a black hole, but opening out again in some other part of the universe.

ether

hypothetical invisible medium that was formerly thought to be required for the propagation of electromagnetic waves and thought to fill space throughout the universe.

Inverse-Square Law

intensity = 1/distance2

inverse-square law

law relating to the intensity of an effect to the inverse square of the distance from the cause. Gravity, electric, magnetic, light, sound, and radiation phenomena follow the inverse-square law.

force field

that wich exists in the space surrounding a mass, electric charge, or magnet, so that another mass, electric charge, or magnet introduced into this region will experience a force.

weight

the force that an object exerts on a supporting surface (or, if suspended, in a supporting string) - often, but not always, due to the force of gravity.

neap tide

tide that occurs when the Moon is halfway between a new Moon and a full Moon, in either direction. The tides due to the Sun and the Moon partly cancel, so that the high tides are lower than average and the low tides are not as low as average.

simple harmonic motion

vibratory or periodic motion, like that of a pendulum, in which the force acting on the vibrating body is proportional to its displacement from its central equilibrium position and acts toward that position.

inversely

when two values change in opposite directions, so that if one increases and the other decreases by the same factor, they are said to be inversely proportional to each other.