Module 8: Gravity

If the moon were twice its distance from earth, but with the same force of gravity between earth and the moon, tidal effects on earth's oceans would be... a) less b) no different c) greater

a) less

On earths surface Mo who weighs 400 N, measures his weight at the top of a hype-tall tower extending one earth radius into space, where he measures his weight to be about... a) 100 N b) 0 N c) 400 N d) none of these e) 200 N

a) 100 N

A clever merchant buys and sells gold by weight at different elevations. Assuming she maintains the same selling price, how would she make a profit? a) buy at a high elevation and sell at a low elevation b) disregard elevation because it makes absolutely no difference c) buy at a low elevation and sell at a high elevation

a) but at a high elevation and sell at a low elevation

According to Newton, doubling the distance between two interacting objects... a) divides by 4 the gravitational force between them b) multiplies by 2 the gravitational force between them c) divides by 2 the gravitational force between them d) multiplies by 4 the gravitational force between them

a) divides by 4 the gravitational force between them

An object located exactly between earth and the moon would be more attracted to the ... a) earth b) neither of these c) moon

a) earth

The chief cause of ocean tides is that the moon... a) has a force of gravity that differs on opposite sides of the planet b) and the sun are in conjunction at high tides and in opposition at low tides c) has a force of gravity that is greater on the earth than the sun

a) has a force of gravity that differs on the opposite sides of the planet

If earths mass increases while its radius remains unchanged, then your weight would... a) increase also b) decrease c) stay the same

a) increase also

Two large asteroids in the deep space float toward each other due to gravity. As they become closer, their acceleration... a) increases b) remains constant c) decreases

a) increases

When the distance between two planets decreases by half, what happens to the force of gravity between them? a) it increases to four times as much b) it decreases by one-quarter c) it increases to twice as much d) it decreases by one-half e) it stays the same

a) it increases to four times as much

What change in earths acceleration around the sun occurs if the sun suddenly becomes a black hole? a) it would stay the same b) it would cease to exist c) it would increase d) it would decrease

a) it would stay the same

How can there to be only one tide per day on earth? a) none of these b) if the moon were more massive than earth c) if the suns influence on the tides were negligible d) if the moons mass were small - only a few kilograms e) if the earth and moon were equally massive

a) none of these

An apple twice as far from the ground as one on the same tree has a weight of... a) practically the same weight b) 1/4 as much c) 1/2 as much

a) practically the same weight

If the mass of the sun and planets were to double, with no changes in size, then your weight on earth would... a) quadruple b) be eight as much as now c) be the same d) double

a) quadruple

An object is placed exactly halfway between the Earth and sun. The object will fall toward... a) the sun b) the Earth

a) the sun

As the sun gets closer each January due to earth eccentric orbit, what happens to ocean tides? a) they get more pronounced b) they diminish c) this has no particular effect

a) they get more pronounced

When a force of 450 N acts on an asteroid the direction of that force is... a) toward the asteroid b) toward the sun c) away from the asteroid

a) toward the asteroid

While flying in a jet plane you feel your normal weight, whereas in an orbiting spaceship you don't, because... a) you are without support forces b) you are beyond the main pull of earths gravity c) you are above the earths atmosphere d) all of these

a) you are without support forces

A bullet fired from a horizontally held rifle hits the ground 0.6 seconds. If it were fired with twice the velocity, the bullet would have hit the ground in... a) less than 0.6 s b) 0.6 s c) more than 0.6 s

b) 0.6 s

How many tidal bulges would show on the moon if it had an ocean surface? a) no tidal bulges b) 2 tidal bulges c) 3 tidal bulges d) 1 tidal bulge e) 4 tidal bulges

b) 2 tidal bulges

Which model of gravitation is most recent? a) both of these b) Einsteins theory of gravitation c) neither of these d) newtons theory of gravitation

b) Einsteins theory of gravitation

If you stood on the surface of Jupiter, your weight would be three times that of earth, even though Jupiter is 300 times the mass of earth. How so? a) you are 100 times more weightless there b) Jupiters radius is 10 times the earths surface c) there is no atmosphere on Jupiters surface d) Jupiter is significantly farther from the sun e) your mass is 100 times less on Jupiter

b) Jupiters radius is 10 times the earths surface

If our sun were twice as massive, its pull on earth would double... a) as would earths pull on the sun b) actually, the suns pull on earth would quadruple c) but earths pull on the sun would remain the same

b) actually, the suns pull on earth would quadruple

Does earth gravity act on inhabitants of an orbiting space station? a) never b) always c) sometimes

b) always

When in an elevator that drops in free fall you'll find that your... a) acceleration is zero b) apparent weight is zero c) all of these d) gravitational interaction with the earth is zero

b) apparent weight is zero

Tiny nano-tidal forces that act on the human body most likely originate from the... a) sun b) earth c) moon

b) earth

A friction-free immense perfectly flat plane on earths curved surface extends thousands of miles from the point of contact. An object set gliding outward from this point eventually slows down 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

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

If earth shrinks to a smaller diameter while keeping the same mass, your weight would... a) decrease b) increase c) not change

b) increase

At what phase of the moon are ocean tides lowest? a) the phase of the moon is not related to tidal effects b) new or full moon c) a half moon d) a quarter moon

b) new or full moon

Consider an alien civilization living in the zero gravity inner space of a perfectly round hollow planet. If a continent-sized hole is cut to allow access to outer space, what happens to their inner space gravitational field? a) it remains zero b) non-zero, directed away from the hole c) non-zero, directed toward the hole

b) non-zero, directed away from the hole

What must occur for significant tidal effects from the moon on a human body? a) all of these b) parts of the body would have to be appreciably closer to the moon than other parts c) the body would have to be primarily in the liquid state d) the earths gravitation would have to be incredibly small

b) parts of the body would have to be appreciably closer to the moon than other parts

An immense perfectly flat friction-free bowling alley is centered on earth's curved surface and extends four kilometers both ways from the point of contact making a total length of 8 kilometers. From one ends bowling ball is gently released. What happens next? a) the ball stays where it is b) the ball rolls the full length back and forth indefinitely c) the ball rolls to a stop upon reaching the center d) the ball rolls to the other side and then stops

b) the ball rolls the full length back and forth indefinitely

Between the sun and the earth, which exerts the strongest tidal effect on your body? a) the sun b) the earth c) the moon

b) the earth

How would the force due to gravity change between earth and the sun if the sun suddenly shrunk to a black hole? a) the force would be less b) the force would be the same c) the force would be greater

b) the force would be the same

Which is most responsible for the ocean tides? a) the sun b) the moon

b) the moon

Which pulls on the oceans of Earth with a greater force? a) the sun b) the moon

b) the moon

Gravitational force acting on an orbiting spaceship is... a) nearly zero b) the same as the ship's weight on the earths surface c) almost as much as the ships weight on the earths surface

b) the same as the ship's weight on the earths surface

The force due to gravity on a 500 N woman standing on Earths surface is... a) 50 N b) 250 N c) 500 N d) 5000 N

c) 500 N

The gravitational field of the earth extends... a) only above and beyond the earths surface and cancels inside the earth b) neither of these c) both inside and outside the earth and throughout the entire universe

c) both inside and outside the earth and throughout the entire universe

If the earth had half its current mass but the same size, your weight would... a) stay the same b) decrease to one quarter your original weight c) decrease to one half your original weight d) none of these

c) decrease to one half your original weight

How far must you travel to remove yourself from earths gravity? a) to a region beyond the solar system b) to the halfway point to the moon c) forget it; you can't travel far enough d) to a region above the earths atmosphere

c) forget it; you can't travel far enough

The direction of earths gravitational field is... a) opposite to the direction of gravitational attraction b) away from the center of gravity of an object c) in the same direction as the gravitational attraction

c) in the same direction as the gravitational attraction

If the moon had twice its mass while remaining in its same orbit ocean tides on earth would be... a) smaller b) unequal in size c) larger d) not significantly different

c) larger

A pair of planets attract each other gravitationally. If both their masses double and distance of separation also doubles, the force on them is... a) twice as much b) one quarter c) none of these d) half as much e) four times as much

c) none of these

How can all oceans on Earth have high tides simultaneously? a) if the sun did not rotate b) if the sun did not revolve c) none of these choices are correct d) if the moon did not rotate e) if the moon did not revolve

c) none of these choices are correct

Which of these most increases the force due to gravity on you: burrow deep inside a planet, or stand on a planet with a shrinking radius? a) both of these b) burrowing deep inside the planet c) standing on a planet with a shrinking radius d) neither of these

c) standing on a planet with a shrinking radius

Two large rocks in deep space float toward each other due to gravity. As they get closer, the force gets... a) to be no different remaining the same b) weaker c) stronger d) weaker, then stronger e) stronger, then weaker

c) stronger

When a star collapses to become a black hole, what change occurs in its mass? a) the mass decreases b) the mass increases c) the mass remains the same

c) the mass remains the same

Although both the moon and the sun pull o the earths oceans , tides are due mostly to the... a) the sun b) both contribute equally c) the moon

c) the moon

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

c) the remains of a giant star that has undergone gravitational collapse

In the period of one day, how do the ocean tides rise and fall across the planet? a) they rise and fall at the same time everywhere b) the rise and fall the same time and the same height everywhere c) the rise and fall at different times and different heights almost everywhere d) the rise and fall the same height everywhere

c) the rise and fall at different times and different heights almost everywhere

Between the moon and the sun pulling on the earth's oceans, which pulls with greater force? a) the moon b) both pull the same c) the sun

c) the sun

Between the moon and an apple held over your head, which exerts a greater tidal effect? a) the moon b) more information is needed c) the watermelon

c) the watermelon

What effect does a solar eclipse have an ocean tides? a) they are extra low b) they are not particularly different c) they are extra high

c) they are extra high

When weighing yourself at high noon, Earth pulls you downward while the sun pulls you upward. Why does the sun not affect your weight? a) the weighing scale is calibrated only in earth weight b) the sun's pull is cancelled by the gravitation of other celestial bodies c) you, the scale, and the earth are in free fall (in orbit) around the sun d) because of tidal effects in the "solid" earth e) the suns pull on you is negligibly small

c) you, the scale, and the earth are in free fall (in orbit) around the sun

What effect on your weight occurs if somehow the sun doubled its mass? a) your weight would quadruple b) your weight would double c) your weight would not change

c) your weight would not change

An elevator is in free fall. An occupant inside has a weight of... a) slightly more than zero b) none o these c) zero d) mass x acceleration before zero

c) zero

If the moon were covered with water, tidal effects caused by the Earth would find the moon with... a) 4 tidal bulges b) 3 tidal bulges c) 1 tidal bulge d) 2 tidal bulges

d) 2 tidal bulges

An asteroid exerts a 360 N gravitational force on a nearby spacecraft. If the spacecraft moves to a position three times as far from the center of the asteroid, the force will be... a) 360 N b) 1080 N c) 120 N d) 40 N

d) 40 N

Suppose you travel down a cave halfway to a planets center. If the density of the planet is uniform, how has your weight changed compared to its value on the surface? a) the same as at the surface b) by three-quarters c) by one-quarter d) by one-half e) your weight is now zero

d) by one-half

Imagine a tunnel drilled straight down to earth's other side. With a clear path and no air resistance, what happens to a stone dropped down this tunnel? a) it comes to a stop at the center of the earth b) it speeds up until it reaches the other side of the earth c) it slows down until it reaches the center d) it speeds up until it gets to the center of the earth

d) it speeds up until it gets to the center of earth

A black hole is invisible due to its... a) mass b) size c) color d) surface escape velocity

d) surface escape velocity

Why do you weigh a little bit less at the bottom of a skyscraper than you do in an open nearby field of the same elevation? a) none of these b) both of these c) the gravitational field is shielded inside the building d) the mass of the building attracts you upward slightly

d) the mass of the building attracts you upward slightly

An explorer discover a planet with a thin uniform crust but empty inside. At a point halfway from the surface to the center she finds her weight is... a) one-quarter of your weight on the surface b) three-quarters of your weight on the surface c) the same as at the surface d) zero e) one-half of your weight on the surface

d) zero

A 360 N force acts on an asteroid. When it is three times farther away the force is... a) 1080 N b) 120 N c) zero d) 360 N e) 40 N

e) 40 N

Why are there no tides in an olympic-sized swimming pool? a) tides are only observed at night b) the pool is shallow compares to the ocean c) the effects are masked by the much stronger pull of earths gravity d) the gravitation on the relatively small mass of eater is negligibly small e) all parts of the pool are practically the same distance from the moon

e) all parts of the pool are practically the same distance from the moon

How do tidal forces arise? a) from a combination of any kind of forces acting on an body b) from two or more sources of gravitation c) from the inverse-square law d) from unequal fluid flow e) from unequal forces acting on different parts of a body

e) from unequal forces acting on different parts of a body