Physics Practice Test - Gravity and Tides

both of these

If the sun were twice as massive A) its pull on the Earth would double. B) the pull of the Earth on the sun would double.C) both of these D) neither of these

apparent weight for you

Inside a freely-falling elevator, there would be no A) gravitational force on you. B) apparent weight for you. C) both of these D) none of these

apparent weight is zero

Inside a freely-falling runaway elevator, your A) acceleration is zero.B) apparent weight is zero.C) gravitational interaction with the Earth is zero. D) all of these E) none of these

simply the remains of a giant star that has undergone gravitational collapse

A black hole is A) an empty region of space with a huge gravitational field. B) a small region that contains the mass of many galaxies.C) simply the remains of a giant star that has undergone gravitational collapse.

buy at a high altitude and sell at a low altitude

A supplier wants to make a profit by buying metal by weight at one altitude and selling it at the same price per pound at another altitude. The supplier should A) buy at a high altitude and sell at a low altitude. B) buy at a low altitude and sell at a high altitude. C) disregard altitude because it makes no difference.

Both forces are the same

A very massive object A and a less massive object B move toward each other under the influence of gravitation. Which force, if either, is greater? A) the force on A B) the force on B C) Both forces are the same.

100 N

A weight watcher who normally weighs 400 N stands on top of a very tall ladder so she is one Earth radius above the Earth's surface. How much would she weigh there?A) 0 B) 100 N C) 200 N D) 400 N E) none of these

divides by 4 the gravitational force between them

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

greater the gravitational force between them

According to Newton, the greater the masses of interacting objects, the A) less the gravitational force between them. B) greater the gravitational force between them. C) greater the force between them by the square of the masses.

40 N

An asteroid exerts a 360-N gravitational force on a nearby spacecraft. If the spacecraft moves to a point 3 times as far from the center of the asteroid, the force will be A) zero. B) 40 N. C) 120 N. D) 360 N. E) 1080 N.

toward the asteroid

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

Earth

An object is placed exactly halfway between the Earth and moon. The object will fall toward the A) Earth. B) moon. C) neither of these

none of these

Consider two planets in space that gravitationally attract each other. If the masses of both planets are doubled, and the distance between them is also doubled, then the force between them is A) one quarter. B) half as much. C) twice as much. D) four times as much. E) none of these

always false

For the astronauts inside the orbiting space shuttle, there is no force of Earth gravity acting on them. This statement is A) always true while in orbit. B) sometimes true while in orbit. C) always false.

Forget it; you can't travel far enough

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

gravity will pull in a non-perpendicular direction as the block gets farther out on the plane

If a block is set sliding on a huge frictionless plane in contact with the Earth, it will NOT continue to move at constant speed because A) of its inertia.B) gravity will pull in a non-perpendicular direction as the block gets farther out on the plane. C) gravity gets weaker as distance increases. D) it is not free from the shackles of Earth's gravity.

decrease to one half your original weight

If the Earth's mass decreased to one-half its original mass with no change in radius, then your weight would A) decrease to one quarter your original weight. B) decrease to one half your original weight.C) stay the same. D) none of these

increase also

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

increase

If the radius of the Earth somehow decreased with no change in mass, your weight would A) increase. B) not change. C) decrease.

the same

If the sun collapsed to a black hole, the Earth's gravitational attraction to it would be A) more. B) less. C) the same.

not change

If the sun somehow became twice as massive, your weight as normally measured here on earth would A) double. B) quadruple. C) not change.

quadruple

If your mass, the mass of the Earth, and the mass of everything in the solar system were twice as much as it is now, yet everything stayed the same size, your weight on Earth would A) be the same. B) double. C) quadruple.D) be eight times as much as now.E) none of these

that gravity is universal

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

are in free fall and experience apparent weightlessness

Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in the orbiting space shuttle do not. This is because passengers in the space shuttle are A) beyond the main pull of Earth's gravity.B) above the Earth's atmosphere. C) are in free fall and experience apparent weightlessness. D) all of these E) none of these

stay the same

The Earth is currently accelerating toward the sun (centripetal acceleration). If the sun collapsed into a black hole, this acceleration would A) increase. B) decrease. C) stay the same. D) cease to exist.

both inside and outside the Earth and throughout the entire universe

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

almost as much as the shuttle's weight on the Earth's surface

The amount of gravitational force that acts on the space shuttle while in orbit is A) nearly zero. B) almost as much as the shuttle's weight on the Earth's surface. C) the same as the shuttle's weight on the Earth's surface.

in the same direction as the gravitational attraction

The direction of a gravitational field is A) in the same direction as the gravitational attraction. B) away from the center of gravity of an object. C) opposite to the direction of gravitational attraction.

surface escape velocity

The factor most directly responsible for making a black hole invisible is its A) size.B) mass.C) color. D) surface escape velocity. E) none of these

stand on a planet with a radius that is shrinking

The force of gravity acting on you will increase if you A) burrow deep inside the planet. B) stand on a planet with a radius that is shrinking. C) both of these D) none of these

practically the same weight

The force of gravity acts on all apples on an apple tree. Some apples are twice as far from the ground as others. These twice-as-high apples, for the same mass, have A) 1/4 the weight. B) 1/2 the weight. C) practically the same weight.

is greater on oceans closer to the moon and less on oceans farther from the moon

The main reason ocean tides exist is that the pull of the moon A) and sun are in conjunction at high tides and in opposition at low tides. B) is greater on oceans closer to the moon and less on oceans farther from the moon. C) is greater on the Earth because the moon is closer to Earth. D) and the sun on the oceans are in opposite directions. E) none of these

Jupiter's radius is 10 times the Earth's radius

The planet Jupiter is about 300 times as massive as Earth, yet on its surface you would weigh only about 3 times as much. This is because A) your mass is 100 times less on Jupiter. B) Jupiter is significantly farther from the sun. C) Jupiter's radius is 10 times the Earth's radius. D) you are 100 times more weightless there. E) none of these

moon has a sufficient tangential speed

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

unequal forces acting on different parts of a body

Tidal forces in general are the result of A) two or more sources of gravitation. B) a combination of any kind of forces acting on a body. C) unequal forces acting on different parts of a body. D) the inverse-square law. E) unequal fluid flow.

increases

Two objects move toward each other because of gravity. As the objects get closer and closer, the acceleration of each A) increases. B) decreases.C) remains constant.

increases

Two objects move toward each other because of gravity. As the objects get closer and closer, the force between them A) increases.B) decreases.C) increases, then decreases.D) decreases, then increases. E) remains constant.

500 N

What is the force of gravity on a 500-newton woman standing on the Earth's surface? A) 50 N B)250 N C) 500 N D) 5000 N E) none of these

remains the same

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

increases to four times as much

When the distance between two stars decreases by half, the force between them A) decreases by one-quarter. B) decreases by one-half. C) increases to twice as much. D) increases to four times as much. E) stays the same.

you, the scale, and the Earth are freely falling around the sun

When you step on a weighing scale at noon, the Earth pulls you down and the overhead sun pulls you upward. The reason the sun's pull doesn't decrease your weight at noon is because A) the sun's pull on you is negligibly small. B) the weighing scale is calibrated only in Earth weight. C) you, the scale, and the Earth are freely falling around the sun. D) the sun's pull is cancelled by the gravitation of other celestial bodies. E) of tidal effects in the "solid" Earth.

the moon

Which is most responsible for the ocean tides? A) the moon B) the sun C) Both contribute equally.