Mastering Physics Set 1 Midterm #1

A certain planet has an escape speed V. If another planet of the same size has twice the mass as the first planet, its escape speed will be V V/2 V/√2 √2V 2V

√2V

Which of the following quantities represent mass? Check all that apply. 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? Check all that apply. 12.0 lbs 0.34 g 120 kg 1600 kN 0.34 m 411 cm 899 MN

12.0 lbs 1600 kN 899 MN

A

Consider the earth following its nearly circular orbit (dashed curve) about the sun.(Figure 2) The earth has mass mearth=5.98×10^24kg and the sun has mass msun=1.99×10^30kg. They are separated, center to center, by r=93 million miles=150 million km. 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) .

5.7 m/s^2

If the acceleration due to gravity on the earth is 9.8 m/s2, what is the acceleration due to gravity on Rams?

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 force is toward the sun.

With the sun and the earth back in their regular positions, consider a space probe with mass mp=125kg 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?(Figure 4) Ignore the effects of other massive objects in the solar system, such as the moon and other planets. The force is toward the sun. The force is toward the earth. There is no net force because neither the sun nor the earth attracts the probe gravitationally at the midpoint. There is no net force because the gravitational attractions on the probe due to the sun and the earth are equal in magnitude but point in opposite directions, so they cancel each other out.

A very small round ball is located near a large solid sphere of uniform density. The force that the large sphere exerts on the ball is independent of the mass of the ball. is exactly the same as it would be if all the mass of the sphere were concentrated at the center of the sphere. is independent of the mass of the sphere. is approximately the same as it would be if all the mass of the sphere were concentrated at the center of the sphere. can only be calculated using calculus.

is exactly the same as it would be if all the mass of the sphere were concentrated at the center of the sphere.

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

Very far from earth (at R=∞), a spacecraft has run out of fuel and its kinetic energy is zero. If only the gravitational force of the earth were to act on it (i.e., neglect the forces from the sun and other solar system objects), the spacecraft would eventually crash into the earth. The mass of the earth is Me and its radius is Re. Neglect air resistance throughout this problem, since the spacecraft is primarily moving through the near vacuum of space. Find the speed se of the spacecraft when it crashes into the earth. Express the speed in terms of Me, Re, and the universal gravitational constant G.

se = sqrt(2GMe/Re)

Very far from earth (at R=∞), a spacecraft has run out of fuel and its kinetic energy is zero. If only the gravitational force of the earth were to act on it (i.e., neglect the forces from the sun and other solar system objects), the spacecraft would eventually crash into the earth. The mass of the earth is Me and its radius is Re. Neglect air resistance throughout this problem, since the spacecraft is primarily moving through the near vacuum of space. Now find the spacecraft's speed when its distance from the center of the earth is R=αRe, where the coefficient α≥1 Express the speed in terms of se and α.

sα = se/√α

If the mass of the earth and all objects on it were suddenly doubled, but the size remained the same, the acceleration due to gravity at the surface would become 4 times what it now is. 1/4 of what it now is. 2 times what it now is. 1/2 of what it now is. the same as it now is.

2 times what it now is.

Consider the earth following its nearly circular orbit (dashed curve) about the sun.(Figure 2) The earth has mass mearth=5.98×10^24kg and the sun has mass msun=1.99×10^30kg. They are separated, center to center, by r=93 million miles=150 million km. What is the magnitude of the gravitational force acting on the earth due to the sun?

3.53×10^22 N

Planet Z-34 has a mass equal to 1/3 that of Earth, a radius equal to 1/3 that of Earth, and an axial spin rate 1/2 that of Earth. With g representing, as usual, the acceleration due to gravity on the surface of Earth, the acceleration due to gravity on the surface of Z-34 is g/9. 6g. g/3. 9g. 3g.

3g.

According to Newton's law of universal gravitation, the gravitational force on the object is Fg=G(memo/r^2e) = (Gme/r^2e)mo, where me is the mass of the earth and re is the distance between the object and the center of the earth (i.e., re = radius of the earth = 6.38×10^3km). What is the value of the composite constant (Gme/r^2e), to be multiplied by the mass of the object mo in the equation above?

9.80 m/s^2

mass remains the same; weight decreases

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

The key to making a concise mathematical definition of escape velocity is to consider the energy. If an object is launched at its escape velocity, what is the total mechanical energy Etotal of the object at a very large (i.e., infinite) distance from the planet? Follow the usual convention and take the gravitational potential energy to be zero at very large distances.

Etotal = 0

Consider the motion of an object between a point close to the planet and a point very very far from the planet. Indicate whether the following statements are true or false. Kinetic energy is conserved. true false

False

g=5.6/1.7^2

If acceleration due to gravity on the earth is g, which formula gives the acceleration due to gravity on Loput? g = 1.7/5.6 g=1.7^2/5.6 g=1.7^2/5.6^2 g=5.6/1.7 g=5.6^2/1.7^2 g=5.6/1.7^2

What is the magnitude of the gravitational force acting on the sun due to the earth? The earth does not exert any gravitational force on the sun. _______________ The earth exerts some force on the sun, but less than 3.53×10^22N because the earth, which is exerting the force, is so much less massive than the sun. _______________ The earth exerts 3.53×10^22N of force on the sun, exactly the same amount of force the sun exerts on the earth found in Part A. _______________ The earth exerts more than 3.53×10^22N of force on the sun because the sun, which is experiencing the force, is so much more massive than the earth.

The earth exerts 3.53×10^22N of force on the sun, exactly the same amount of force the sun exerts on the earth found in Part A.

A baseball is located at the surface of the earth. Which statements about it are correct? (There may be more than one correct choice.) The gravitational force on the ball is independent of the mass of the ball. The earth exerts a much greater gravitational force on the ball than the ball exerts on the earth. The gravitational force on the ball is independent of the mass of the earth. The ball exerts a greater gravitational force on the earth than the earth exerts on the ball. The gravitational force on the ball due to the earth is exactly the same as the gravitational force on the earth due to the ball.

The gravitational force on the ball due to the earth is exactly the same as the gravitational force on the earth due to the ball.

Consider the motion of an object between a point close to the planet and a point very very far from the planet. Indicate whether the following statements are true or false. The angular momentum about the center of the planet and the total mechanical energy will be conserved regardless of whether the object moves from small R to large R (like a rocket being launched) or from large R to small R (like a comet approaching the earth). true false

True

Consider the motion of an object between a point close to the planet and a point very very far from the planet. Indicate whether the following statements are true or false. Total mechanical energy is conserved. true false

True

Pentune

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

Consider the motion of an object between a point close to the planet and a point very very far from the planet. Indicate whether the following statements are true or false. Angular momentum about the center of the planet is conserved. true false

true

Find the escape velocity ve for an object of mass m that is initially at a distance R from the center of a planet of mass M. Assume that R≥Rplanet, the radius of the planet, and ignore air resistance. Express the escape velocity in terms of R, M, m, and G, the universal gravitational constant.

ve = sqrt(2GM/R)

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