Multiple Choice
Identify the
choice that best completes the statement or answers the question.
|
|
|
1.
|
An astronaut is in a capsule in a stable orbit,
about two Earth radii from the center of Earth. Her weight is
a. | zero N. | b. | the same as on the surface of Earth. | c. | about one-half of her weight on the surface of
Earth. | d. | about one-third of her weight on the surface of
Earth. | e. | about one-quarter of her weight on the surface of
Earth. |
|
|
|
2.
|
A satellite encircles Mars at a distance above its
surface equal to 3 times the radius of Mars. The acceleration of gravity at the satellite, as
compared to the acceleration of gravity on the surface of Mars, is
a. | one-ninth as much. | b. | zero. | c. | the
same. | d. | one-third as much. | e. | one-sixteenth as much. |
|
|
|
3.
|
A satellite is orbiting Earth in a circular orbit
of radius r when it fires its rockets and acquires speed rapidly. Following this, the
satellite's orbit
a. | becomes hyperbolic. | b. | stays circular but with a larger radius. | c. | stays circular but with a smaller radius. | d. | becomes elliptical. | e. | none of the
above |
|
|
|
4.
|
What is the ratio of potential energy to total
energy for a planet in a circular orbit around the Sun?
|
|
|
5.
|
What is the ratio of potential energy to kinetic
energy for a comet that has just enough energy to escape from the Sun's gravitational
field?
|
|
|
6.
|
How does the escape speed from Mars compare with
that of the Earth?
[ MEarth=9.31* MMars ; REarth=1.88 * RMars ]
a. | 222.% | b. | 22.5% | c. | 44.9% | d. | 66.2% | e. | 20.2% |
|
|
|
7.
|
What would be the weight of a 59.1-kg astronaut on
a planet with the same density as Earth and having twice Earth's radius?
a. | 580 N | b. | 290 N | c. | 1160
N | d. | 2320 N | e. | 1200 N |
|
|
|
8.
|
The hydrogen atom consists of a proton of mass 1.67
× 10-27 kg and an orbiting electron of mass 9.11 × 10-31 kg. In one of its orbits,
the electron is 5.3 × 10-11 m from the proton. What is the mutual attractive gravitational
force between the electron and proton?
a. | 1.8 × 10-47 N | b. | 3.6 × 10-47 N | c. | 5.4 × 10-47
N | d. | 7.0 × 10-47 N | e. | 9.3 × 10-47 N |
|
|
|
9.
|
At what altitude should a satellite be placed into
circular orbit so that its orbital period is 48.0 hours? The mass of the earth is 5.976 ×
1024 kg and the radius of the earth is 6.378 × 106 m.
a. | 4.22 × 107 m | b. | 7.58 × 107 m | c. | 8.22 × 107
m | d. | 6.07 × 107 m | e. | 6.71 × 107 m |
|
|
|
10.
|
Sirius A and Sirius B constitute a binary star pair
in which the stars orbit their common center of mass with a period of 49.9 years. The stars are 2.40
× 1012 m apart. Assume that the two stars have equal masses and that they move in a circle about
their common center of mass. What is the mass of each star? G = 6.67 x 10-11
N·m2/kg2.
a. | 5.41 × 1030 kg | b. | 2.70 × 1030 kg | c. | 7.55 × 1030
kg | d. | 3.30 × 1030 kg | e. | 1.65 × 1030 kg |
|
|
|
11.
|
Suppose that the Sun were to collapse under its own
gravitational pull. To what radius would it have to be reduced in order for the escape velocity to be
equal the speed of light, 3.00 x 108 m/s? The mass of the Sun is 2.00 x 1030 kg and G = 6.67 x
10-11 N·m2/kg2.
a. | 2.96 km | b. | 1.48 km | c. | 1.52
km | d. | 2.10 km | e. | None of the other choices is correct. |
|
|
|
12.
|
In 1994, fragments of Comet P/Shoemaker-Levy 9
collided with Jupiter. Assume that these fragments came from an infinite distance away with zero
initial speed and fell into Jupiter. What was their speed when they arrived at Jupiter's
surface? Jupiter has a mass of 1.90 × 1027 kg and a radius of 71.4 × 106 m, and G =
6.67 x 10-11 N·m2/kg2.
a. | 10,400 m/s | b. | 11,200 m/s | c. | 35,500
m/s | d. | 42,100 m/s | e. | 59,600 m/s |
|
|
|
13.
|
Asteroid 433 Eros is one of the largest near-Earth
asteroids. For purposes of this problem, assume it is spherical. The value of g at its surface
is 0.0060 m/s2 and the escape velocity is only 10.1 m/s. What is the mass of Eros? G =
6.67 x 10-11 N·m2/kg2.
a. | 2.3 × 1016 kg | b. | 3.5 × 1012 kg | c. | 6.5 ×
1015 kg | d. | 4.9 × 1014 kg | e. | 6.7 × 1013 kg |
|
|
|
14.
|
A space exploration satellite is orbiting a
spherical asteroid whose mass is 4.65 × 1016 kg and whose radius is 39,600 m, at an altitude of
12,400 m above the surface of the asteroid. In order to make a soft landing, Mission Control sends it
a signal to fire a short burst of its retro rockets to change its speed to one that will put the
satellite in an elliptical orbit with a periapsis (the distance of closest approach, as measured from
the center of the asteroid) equal to the radius of the asteroid. What is the speed of the satellite
when it reaches the surface of the asteroid?
G = 6.67 x 10-11 N·m2/kg2.
a. | 4.32 m/s | b. | 6.11 m/s | c. | 7.18
m/s | d. | 9.43 m/s | e. | 5.74 m/s |
|
|
|
15.
|
A 700-kg satellite is in an elliptical orbit around
Earth with a perigee (the point of closest approach) of 7.50 × 106 m from the center of
Earth and an apogee (the furthest point from the center of Earth) of 11.5 × 106 m. What is
the total energy of the satellite? The mass of Earth is 5.97 × 1024 kg and G = 6.67 x
10-11 N·m2/kg2.
a. | -4.51 × 1010 J | b. | -3.10 × 1010 J | c. | -2.08 × 1010
J | d. | -1.04 × 1010 J | e. | -1.47 × 1010J |
|
|
|
16.
|
For an object that travels at a fixed speed along a
circular path, the acceleration of the object is
a. | larger in magnitude the smaller the radius of the
circle. | b. | in the same direction as the velocity of the
object. | c. | smaller in magnitude the smaller the radius of the
circle. | d. | in the opposite direction of the velocity of the
object. | e. | zero. |
|
|
|
17.
|
A roller coaster car (mass = M) is on a track that
forms a circular loop (radius = r) in the vertical plane. If the car is to just maintain
contact with the track at the top of the loop, what is the minimum value for its speed at that
point?
a. | rg | b. | 2rg | c. | (rg)1/2 | d. | (2rg)1/2 | e. | (0.5rg)1/2 |
|
|
|
18.
|
In a carnival ride, passengers stand with their
backs against the wall of a cylinder. The cylinder is set into rotation and the floor is lowered away
from the passengers, but they remain stuck against the wall of the cylinder. For a cylinder with a
2.0-m radius, what is the minimum speed that the passengers can have for this to happen if the
coefficient of static friction between the passengers and the wall is 0.25?
a. | 8.9 m/s | b. | 2.3 m/s | c. | 3.0
m/s | d. | 4.9 m/s | e. | It depends on the mass of the
passengers. |
|
|
|
19.
|
A 600-kg car is going around a curve with a radius
of 120 m that is banked at an angle of 20° with a speed of 24.5 m/s. What is the minimum
coefficient of static friction required for the car not to skid?
a. | 0.12 | b. | 0.24 | c. | 0.36 | d. | 0.48 | e. | 0.60 |
|
|
|
20.
|
A 600-kg car is going over a curve with a radius of
120 m that is banked at an angle of 25° with a speed of 30.0 m/s. The coefficient of static
friction between the car and the road is 0.30. What is the normal force exerted by the road on the
car?
a. | 1590 N | b. | 3430 N | c. | 3620
N | d. | 7240 N | e. | 5330 N |
|
|
|
21.
|
A 0.30-kg rock is swung in a circular path and in a vertical plane on a
0.25-m-length string. At the top of the path, the angular speed is 12.0 rad/s. What is the tension in
the string at that point?
a. | 7.9 N | b. | 16 N | c. | 18
N | d. | 83 N |
|
|
|
22.
|
At what speed will a car round a 52-m-radius curve, banked at a 45° angle, if no friction is required between the road and tires to prevent
the car from slipping? (g = 9.8 m/s2)
a. | 27 m/s | b. | 17 m/s | c. | 23
m/s | d. | 35 m/s |
|
|
|
23.
|
Consider a child who is swinging. As she reaches the lowest point in her
swing:
a. | the tension in the rope is equal to her weight. | b. | the tension in the
rope is equal to her mass times her acceleration. | c. | her acceleration is downward at 9.8
m/s2. | d. | none of the above. |
|
|
|
24.
|
An airplane in a wide sweeping "outside" loop can create zero gees
inside the aircraft cabin. What must be the radius of curvature of the flight path for an aircraft
moving at 150 m/s to create a condition of "weightlessness" inside the aircraft?
a. | 1 150 m | b. | 1 800 m | c. | 2 300
m | d. | 3 600 m |
|
|
|
25.
|
An Earth satellite is orbiting at a distance from the Earth's surface equal
to one Earth radius (4 000 miles). At this location, the acceleration due to gravity is
what factor times the value of g at the Earth's surface?
a. | There is no acceleration since the satellite is in orbit. | b. | 2 | c. | 1/2 | d. | 1/4 |
|
|
|
26.
|
An asteroid has a perihelion (the orbit's closest approach to the sun) of
1.5 AU and a period of revolution of 8.0 y. What is its greatest distance from the sun (its
aphelion)?
a. | 8.0 AU | b. | 6.5 AU | c. | 4.0
AU | d. | 2.5 AU |
|
|
|
27.
|
According to Kepler's second law, Halley's Comet circles the Sun in an
elliptical path with the Sun at one focus of the ellipse. What is at the other focus of the
ellipse?
a. | nothing | b. | the Earth | c. | The comet itself
passes through the other focus. | d. | The tail of the comet stays at the other
ellipse. |
|
|
|
28.
|
An asteroid is in orbit at 4 times the earth's distance from the Sun. What
is its period of revolution?
a. | one fourth year | b. | 4 years | c. | 8
years | d. | 16 years |
|
|
|
29.
|
Two objects are in circular orbits of different radii around the Sun. Which
object has the highest orbital speed?
a. | The one closest to the Sun. | b. | The one farthest from the
Sun. | c. | Once in orbit around the Sun, all objects have the same orbital speed regardless of
distance from the Sun. It is the greater radius and greater resulting circumference that causes the
object farther from the Sun to take longer to complete an orbit. | d. | This cannot be found
without knowing the relative masses of the objects. |
|
|
|
30.
|
A car is going around a racetrack at constant speed. The curves around the track
have different radii. In which turn is the magnitude of the car's acceleration the
greatest?
a. | It is the greatest in the turn with the greatest radius. | b. | It is the greatest
in the turn with the smallest radius. | c. | The acceleration is zero everywhere because of
the constant speed. | d. | More information is needed to determine the
answer. |
|
