Transcript Conceptual Physical Science 5e — Chapter 4

Conceptual
Physical
Science
5th Edition
Chapter 4:
GRAVITY,
PROJECTILES,
AND SATELLITES
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Gravity was discovered by
A.
B.
C.
D.
Aristotle.
Galileo.
Isaac Newton.
early humans.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Gravity was discovered by
A.
B.
C.
D.
Aristotle.
Galileo.
Isaac Newton.
early humans.
Explanation:
Early humans discovered gravity. Newton’s discovery was that
gravity is universal—existing everywhere.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The concept of free-falling objects applies to
A.
B.
C.
D.
falling apples.
the Moon.
Both of the above.
Neither of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The concept of free-falling objects applies to
A.
B.
C.
D.
falling apples.
the Moon.
Both of the above.
Neither of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the distance between two planets doubles, the force of
gravity between them
A.
B.
C.
D.
doubles.
quadruples.
decreases to half.
decreases to one-quarter.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the distance between two planets doubles, the force of
gravity between them
A.
B.
C.
D.
doubles.
quadruples.
decreases to half.
decreases to one-quarter.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the distance between two planets decreases to half, the
force of gravity between them
A.
B.
C.
D.
doubles.
quadruples.
decreases to half.
decreases to one-quarter.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the distance between two planets decreases to half, the
force of gravity between them
A.
B.
C.
D.
doubles.
quadruples.
decreases to half.
decreases to one-quarter.
Explanation:
Twice as close means four times the force (inverse-square law).
Can you see that if the distance were instead doubled, the force
would be one-quarter?
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When the distance between two stars decreases by
one-tenth, the force between them
A.
B.
C.
D.
decreases to one-tenth.
decreases to one-hundredth.
increases 10 times as much.
increases 100 times as much.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When the distance between two stars decreases by
one-tenth, the force between them
A.
B.
C.
D.
decreases to one-tenth.
decreases to one-hundredth.
increases 10 times as much.
increases 100 times as much.
Explanation:
This refers to the inverse-square law of gravity. Ten times closer
means 100 times the force. Can you see if the distance were
increased by ten the force would be 1/100?
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Consider light from a candle. If you’re five times as far
away, its brightness will look about
A.
B.
C.
D.
one-fifth as much.
one-tenth as much.
one twenty-fifth as much.
the same brightness at any reasonable distance.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Consider light from a candle. If you’re five times as far
away, its brightness will look about
A.
B.
C.
D.
one-fifth as much.
one-tenth as much.
one twenty-fifth as much.
the same brightness at any reasonable distance.
Explanation:
Five times as far, according to the inverse-square law, is 1/25 the
brightness. Likewise for the sound of a chirping cricket!
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Consider a space probe at a distance five times Earth’s
radius. Compared with gravitational force at Earth’s
surface, its gravitational attraction to Earth at this distance
is about
A.
B.
C.
D.
one-fifth as much.
one-tenth as much.
one twenty-fifth as much.
the same gravitation at any reasonable distance.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Consider a space probe at a distance five times Earth’s
radius. Compared with gravitational force at Earth’s
surface, its gravitational attraction to Earth at this distance
is about
A.
B.
C.
D.
one-fifth as much.
one-tenth as much.
one twenty-fifth as much.
the same gravitation at any reasonable distance.
Explanation:
Five times as far (inverse-square law) means 1/25 the gravitational
attraction.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the Earth’s radius somehow shrunk, your weight on the
shrunken surface would be
A.
B.
C.
D.
less.
more.
unchanged.
none of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the Earth’s radius somehow shrunk, your weight on the
shrunken surface would be
A.
B.
C.
D.
less.
more.
unchanged.
none of the above.
Comment:
The idea of surface force increasing when a star shrinks leads to
the huge forces near an ultimate shrunken star—a black hole.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the Sun were twice as massive, its pull on Earth would be
A.
B.
C.
D.
unchanged.
twice as much.
half as much.
four times as much.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
If the Sun were twice as massive, its pull on Earth would be
A.
B.
C.
D.
unchanged.
twice as much.
half as much.
four times as much.
Explanation:
Let the equation for gravity guide your thinking. When one mass is
doubled, with all else being the same, the force doubles.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Strictly speaking, compared with your weight on the
ground, your weight at the top of a very tall ladder would be
A.
B.
C.
D.
less.
more.
no different, really.
none of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Strictly speaking, compared with your weight on the
ground, your weight at the top of a very tall ladder would be
A.
B.
C.
D.
less.
more.
no different, really.
none of the above.
Explanation:
This follows from the inverse-square law.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
According to the equation for gravity, if you travel far
enough from Earth, the gravitational influence of Earth will
A.
B.
C.
D.
reach zero.
still be there.
actually increase.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
According to the equation for gravity, if you travel far
enough from Earth, the gravitational influence of Earth will
A.
B.
C.
D.
reach zero.
still be there.
actually increase.
None of the above.
Explanation:
Look at the gravity equation: as d approaches infinity,
F approaches zero—but never reaches zero.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
You are weightless when you are
A.
B.
C.
D.
in free fall.
without a support force.
infinitely away from all mass.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
You are weightless when you are
A.
B.
C.
D.
in free fall.
without a support force.
infinitely away from all mass.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When an astronaut in orbit around Earth is weightless, he
or she is
A.
B.
C.
D.
beyond the pull of Earth’s gravity.
still in the grip of Earth’s gravity.
in the grip of interstellar gravity.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When an astronaut in orbit around Earth is weightless, he
or she is
A.
B.
C.
D.
beyond the pull of Earth’s gravity.
still in the grip of Earth’s gravity.
in the grip of interstellar gravity.
None of the above.
Comment:
If the astronaut were not in the grip of Earth’s gravity, would his or
her circling the Earth occur? Interstellar gravity plays a
significantly lesser role.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When you stand at rest on a weighing scale, the force due
to gravity on you is
A.
B.
C.
D.
equal in magnitude to the support force of the scale.
almost equal to the support force of the scale.
actually absent.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When you stand at rest on a weighing scale, the force due
to gravity on you is
A.
B.
C.
D.
equal in magnitude to the support force of the scale.
almost equal to the support force of the scale.
actually absent.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Inhabitants in the International Space Station orbiting Earth
are
A.
B.
C.
D.
weightless.
in the grip of Earth’s gravity.
without a support force.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Inhabitants in the International Space Station orbiting Earth
are
A.
B.
C.
D.
weightless.
in the grip of Earth’s gravity.
without a support force.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A ball rolls off the edge of a table and hits the floor below. If
the ball’s speed were somewhat greater, the time to hit the
floor would be
A.
B.
C.
less
the same.
more.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A ball rolls off the edge of a table and hits the floor below. If
the ball’s speed were somewhat greater, the time to hit the
floor would be
A.
B.
C.
less
the same.
more.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A horizontally-moving tennis ball barely clears the net and
barely lands just within the court. If the ball were moving a
bit faster it would land
A.
B.
C.
also within the court.
beyond the court.
a bit longer in time.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A horizontally-moving tennis ball barely clears the net and
barely lands just within the court. If the ball were moving a
bit faster it would land
A.
B.
C.
also within the court.
beyond the court.
a bit longer in time.
Explanation:
Assuming no exotic spin effects, the time of the ball in the air
would be the same whatever its speed. But a bit faster would
send it beyond the court’s border.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The positions of a cannonball are shown at various times
when air resistance isn’t a factor. If the speed were
significantly greater, how high above ground level would
the cannonball be at 4 seconds?
A.
B.
C.
D.
45 m.
60 m.
80 m.
None of these.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The positions of a cannonball are shown at various times
when air resistance isn’t a factor. If the speed were
significantly greater, how high above ground level would
the cannonball be at 4 seconds?
A.
B.
C.
D.
45 m.
60 m.
80 m.
None of these.
Explanation:
Vertical distance is given by ½ gt2 = ½ (10m/s2)(4 s)2 = 80 m.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Figure 4.18 assumes no air resistance. If air resistance
were a significant factor, at 3 seconds the cannonball
would be
A.
B.
C.
D.
lower than 45-m high.
at a reduced horizontal distance.
both of these.
neither of these.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Figure 4.18 assumes no air resistance. If air resistance
were a significant factor, at 3 seconds the cannonball
would be
A.
B.
C.
D.
lower than 45-m high.
at a reduced horizontal distance.
both of these.
neither of these.
Explanation:
Air resistance would lessen both its vertical and its horizontal
components of velocity. So it wouldn’t go as high nor as far
horizontally.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A projectile follows a curved path
A.
B.
C.
D.
when it crosses a gravitational field.
due to a combination of constant horizontal motion and
accelerated downward motion.
called a parabola.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A projectile follows a curved path
A.
B.
C.
D.
when it crosses a gravitational field.
due to a combination of constant horizontal motion and
accelerated downward motion.
called a parabola.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The speed of a bowling ball rolling along a smooth alley is
A.
B.
C.
D.
not affected by gravity.
constant.
Both of the above.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The speed of a bowling ball rolling along a smooth alley is
A.
B.
C.
D.
not affected by gravity.
constant.
Both of the above.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When no air resistance acts on a projectile, its horizontal
acceleration is
A.
B.
C.
D.
g.
at right angles to g.
centripetal.
zero.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When no air resistance acts on a projectile, its horizontal
acceleration is
A.
B.
C.
D.
g.
at right angles to g.
centripetal.
zero.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Without air resistance, the time for a vertically tossed ball to
return to where it was thrown from is
A.
B.
C.
D.
10 m/s for every second in the air.
the same as the time going upward.
less than the time going upward.
more than the time going upward.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Without air resistance, the time for a vertically tossed ball to
return to where it was thrown from is
A.
B.
C.
D.
10 m/s for every second in the air.
the same as the time going upward.
less than the time going upward.
more than the time going upward.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
With air resistance, the time for a vertically tossed ball to
return to where it was thrown from is
A.
B.
C.
D.
10 m/s for every second in the air.
the same as the time going upward.
less than the time going upward.
more than the time going upward.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
With air resistance, the time for a vertically tossed ball to
return to where it was thrown from is
A.
B.
C.
D.
10 m/s for every second in the air.
the same as the time going upward.
less than the time going upward.
more than the time going upward.
Explanation:
Consider a feather tossed upward. It reaches its zenith rather
quickly but falls back to its starting place slowly. The same is true
of a ball tossed in air, though not as pronounced.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When air resistance is negligible, the component of velocity
that doesn’t change for a projectile is the
A.
B.
C.
D.
horizontal component.
vertical component.
a combination of horizontal and vertical components.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
When air resistance is negligible, the component of velocity
that doesn’t change for a projectile is the
A.
B.
C.
D.
horizontal component.
vertical component.
a combination of horizontal and vertical components.
None of the above.
Explanation:
That’s because there is no horizontal force. What can you say
about the vertical component of velocity?
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Air resistance on a projectile
A.
B.
C.
D.
lessens its range.
lessens its height.
Both of the above.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
Air resistance on a projectile
A.
B.
C.
D.
lessens its range.
lessens its height.
Both of the above.
None of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The first person(s) to publish writings about Earth satellites
was
A.
B.
C.
D.
Aristotle.
Isaac Newton.
Albert Einstein.
Hewitt, Suchocki, and Hewitt.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
The first person(s) to publish writings about Earth satellites
was
A.
B.
C.
D.
Aristotle.
Isaac Newton.
Albert Einstein.
Hewitt, Suchocki, and Hewitt.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
In a circular orbit, the gravitational force on a satellite is
A.
B.
C.
D.
constant in magnitude.
at right angles to satellite motion.
directed toward Earth .
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
In a circular orbit, the gravitational force on a satellite is
A.
B.
C.
D.
constant in magnitude.
at right angles to satellite motion.
directed toward Earth.
All of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A satellite in elliptical orbit about Earth travels fastest when
it moves
A.
B.
C.
D.
close to Earth.
far from Earth.
in either direction—the same everywhere.
between the near and far points from Earth.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A satellite in elliptical orbit about Earth travels fastest when
it moves
A.
B.
C.
D.
close to Earth.
far from Earth.
in either direction—the same everywhere.
between the near and far points from Earth.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A satellite in orbit around the Earth is above Earth’s
A.
B.
C.
D.
atmosphere.
gravitational field.
Both of the above.
Neither of the above.
© 2012 Pearson Education, Inc.
Conceptual Physical Science 5e — Chapter 4
A satellite in orbit around the Earth is above Earth’s
A.
B.
C.
D.
atmosphere.
gravitational field.
Both of the above.
Neither of the above.
Explanation:
Don’t say above Earth’s gravitational field! If it were, it wouldn’t
circle Earth.
© 2012 Pearson Education, Inc.