PHY Chapter 06: MasteringPhysics
Which pulls harder gravitationally, the Earth on the Moon , or the Moon on the Earth?
Equal
Which accelerates more? - the Earth - the Moon - They have equal acceleration
The moon
You are explaining to friends why astronauts feel weightless orbiting in the space shuttle, and they respond that they thought gravity was just a lot weaker up there. Convince them and yourself that it isn't so by calculating how much weaker gravity is 300 km above the Earth's surface. Express your answer using two significant figures.
∣Δg/g∣ = 8.8 %
Which of the following quantities represent mass? 12.0 lbs 0.34 g 120 kg 1600 kN 0.34 m 411 cm 899 MN
0.34 g 120 kg
Which of the following quantities would be acceptable representations of weight? 12.0 lbs 0.34 g 120 kg 1600 kN 0.34 m 411 cm 899 MN
12.0 lbs 1600 kN 899 MN Weight is a force and is measured in newtons (or kilo-newtons, mega-newtons, etc.) or in pounds (or tons, megatons, etc.).
Earth's orbit around the Sun is slightly elliptical. Thus, Earth actually gets closer to the Sun during part of the year. What happens to Earth's orbital speed when it is closer to the Sun?
Earth's orbital speed is grater when it is closer to the Sun than when it is farther from the Sun
A satellite of mass 5700 kg orbits the Earth and has a period of 6200 s . Determine the magnitude of the Earth's gravitational force on the satellite. Express your answer using two significant figures.
F = 4.3×10^4 N
Which planet should Punch travel to if his goal is to weigh in at 118 lb? Refer to the table of planetary masses and radii given to determine your answer. - Tehar - Loput - Cremury - Suven - Pentune - Rams
Pentune
Which of the following changes to the earth-sun system would reduce the magnitude of the force between them to one-fourth the value found in Part A? Check all that apply. - Reduce the mass of the earth to one-fourth its normal value. - Reduce the mass of the sun to one-fourth its normal value. - Reduce the mass of the earth to one-half its normal value and the mass of the sun to one-half its normal value. - Increase the separation between the earth and the sun to four times its normal value.
Reduce the mass of the earth to one-fourth its normal value. Reduce the mass of the sun to one-fourth its normal value. Reduce the mass of the earth to one-half its normal value and the mass of the sun to one-half its normal value. The actions in choices A, B, and C would reduce the force to one-fourth its original value by modifying the product of the masses. Increasing the separation distance by a factor of 4 would reduce the force by a factor of 42=16. To reduce the force by only a factor of 4, increase the separation distance by a factor of 2 instead because 22=4.
With the sun and the earth back in their regular positions, consider a space probe with mass mp=125 kg launched from the earth toward the sun. When the probe is exactly halfway between the earth and the sun along the line connecting them, what is the direction of the net gravitational force acting on the probe?Ignore the effects of other massive objects in the solar system, such as the moon and other planets.
The force is toward the sun In calculating these forces, the mass of the probe is the same, as is the distance involved. However, the sun is over 300,000 times as massive as the earth, so at this location the probe is attracted much more strongly toward the sun than toward the earth.
A satellite of mass 5700 kg orbits the Earth and has a period of 6200 s . Determine the altitude of the satellite. Express your answer using one significant figure.
h = 9×10^5 m
After Punch Taut travels to Pentune, what actually happens to his mass and his weight? - mass increases; weight decreases - mass decreases; weight decreases - mass increases; weight increases - mass increases; weight remains the same - mass remains the same; weight decreases - mass remains the same; weight increases - mass remains the same; weight remains the same
mass remains the same; weight decreases
If acceleration due to gravity on the earth is g, which formula gives the acceleration due to gravity on Loput? Mass = 5.6Mearth Radius = 1.7Rearth
mg = GmM/r^2 g5.6/1.7^2
Neutron stars, such as the one at the center of the Crab Nebula, have about the same mass as our sun but a much smaller diameter. If you weigh 675 N on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter of 25.0 km ? Take the mass of the sun to be ms = 1.99×10^30 kg , the gravitational constant to be G = 6.67×10^−11 N⋅m^2/kg^2 , and the acceleration due to gravity at the earth's surface to be g = 9.810 m/s^2.
F = G(m1m2/r^2) m = 68.8 kg r = 1.25 x 10^4 m G = 6.67 x 10^-11 N*m^2/kg^2 wstar = 5.85 x 10^13 N
The gravitational field on the surface of the earth is stronger than that on the surface of the moon. If a rock is transported from the moon to the earth, which properties of the rock change? - mass only - weight only - both mass and weight - neither mass nor weight
weight only
An antenna loosens and becomes detached from a satellite in a circular orbit around the Earth. Describe the antenna's motion subsequently.
The antenna will continue in orbit around the earth
A satellite of mass 5700 kg orbits the Earth and has a period of 6200 s. Determine the radius of its circular orbit. Express your answer using two significant figures.
r = 7.3×10^6 m
What is the value of the composite constant (Gme/re^2), to be multiplied by the mass of the object mo in the equation above? Express your answer numerically in meters per second per second.
radius of earth = 6.38×10^3 km Fg = G(memo/re^2) = (Gme/re^2)mo 9.80 m/s^2
Explain how this enabled an estimate of Pluto's mass. Which of the following can be determined by the observation of the moon (with no calculations)?
the orbital radius of the moon the period of the moon
A certain white dwarf star was once an average star like our Sun. But now it is in the last stage of its evolution and is the size of our Moon but has the mass of our Sun. What would be the speed of a baseball dropped from a height of 3.5 m when it hit the surface? Express your answer using two significant figures.
v = 1.8 x 10^4 m/s
Calculate the speed of a satellite moving in a stable circular orbit about the Earth at a height of 5600 km .
v = 5770 m/s
A certain white dwarf star was once an average star like our Sun. But now it is in the last stage of its evolution and is the size of our Moon but has the mass of our Sun. How much would a 65-kg person weigh on this star? Express your answer using two significant figures.
w = 2.8 x 10^9 N
At the moment shown in the figure of the earth and sun (Figure 2), what is the direction of the gravitational force acting on the earth? The possible directions are displayed in this figure (Figure 3).
A As the earth proceeds around its orbit, the direction of the gravitational force acting on it changes so that the force always points directly toward the sun.
Which of the following statements are true? Check all that apply. - A satellite's velocity and orbital radius are independent of each other. - A satellite's motion is independent of its mass. - A geosynchronous satellite has a period of approximately 28 days. - The launch speed of a satellite determines the shape of its orbit around Earth.
A satellite's motion is independent of its mass. The launch speed of a satellite determines the shape of its orbit around Earth.
What is the magnitude of the gravitational force acting on the earth due to the sun? Express your answer in newtons.
Fg=G(m1m2/r^2), mearth = 5.98 × 1024 kg msun = 1.99×1030 kg. r = 93 million miles = 150 million km 3.53x10^22
If the acceleration due to gravity on the earth is 9.8 m/s2, what is the acceleration due to gravity on Rams? Mass = 9.3 Mearth Radius = 4.0 Rearth
GRams = G*(9.3Mearth)/(4Rearth)^2 = gearth*0.58125 = 9.8*0.58125 = 5.7 m/s^2
An object is lifted from the surface of a spherical planet to an altitude equal to the radius of the planet. As a result, which of the following changes in the properties of the object take place? - mass increases; weight decreases - mass decreases; weight decreases - mass increases; weight increases - mass increases; weight remains the same - mass remains the same; weight decreases - mass remains the same; weight increases - mass remains the same; weight remains the same
Mass remains the same; weight decreases
How this enabled an estimate of Pluto's mass. Express your answer in terms of the variables T, r, and appropriate constants.
Mpluto = (4π^2r^3/GT^2)
Calculate the period of a satellite orbiting the Moon, 140 km above the Moon's surface. Ignore effects of the Earth. The radius of the Moon is 1740 km. Express your answer using two significant figures.
T = 7300 s
Is the centripetal acceleration of Mars in its orbit around the Sun larger or smaller than the centripetal acceleration of the Earth?
The centripetal acceleration of Mars in its orbit around the sun is smaller than the centripetal acceleration on the Earth.
Which of the following statements are true? - The gravitational force between two objects is proportional to the distance between the two objects. - The gravitational force between two objects is inversely proportional to the product of the masses of the two objects. - The gravitational force between two objects is proportional to the square of the distance between the two objects. - The gravitational force between two objects is proportional to the product of the masses of the two objects. - The gravitational force between two objects is inversely proportional to the distance between the two objects. - The gravitational force between two objects is inversely proportional to the square of the distance between the two objects.
The gravitational force between two objects is proportional to the product of the masses of the two objects. The gravitational force between two objects is inversely proportional to the square of the distance between the two objects.
Two planets, planet A and planet B, have the same surface gravity. However, planet B has twice the radius of planet A. How does the mass of planet B compare to the mass of planet A?
The mass of planet B is four times the mass of planet A
What is the magnitude of the gravitational force acting on the sun due to the earth?
The sun exerts 3.53 x 10^22 N of force on the sun, exactly the same amount of force the sun exerts on the earth found in part A.
Which of the following statements is true? Check all that apply. - The sun is located at one of the foci of the planet's elliptical orbits. - The path of the planets around the Sun is elliptical in shape - The Sun is located at the center of the planets' circular orbits - The path of the planets around the Sun is circular in shape
The sun is located at one of the foci of the planet's elliptical orbits. The path of the planets around the Sun is elliptical in shape
A certain white dwarf star was once an average star like our Sun. But now it is in the last stage of its evolution and is the size of our Moon but has the mass of our Sun. Estimate gravity on the surface on this star.
g = 4.38 x 10^7 m/s^2
Describe how careful measurements of the variation in g in the vicinity of an ore deposit might be used to estimate the amount of ore present.
g is greater in its vicinity
