physics hw 9

What is the magnitude of the gravitational force between two 1-kg bodies that are 1 m apart?

6.67 × 10 -11 N

A) Which of the following quantities represent mass? B) Which of the following quantities would be acceptable representations of weight? C) 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? D) 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? E) If acceleration due to gravity on the earth is g, which formula gives the acceleration due to gravity on Loput? F) If the acceleration due to gravity on the earth is 9.8 m/s2, what is the acceleration due to gravity on Rams? G) 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. H) After Punch Taut travels to Pentune, what actually happens to his mass and his weight?

A) 0.34g, 120 kg B) 12.0 lbs, 1600kN, 899MN C) weight only D) mass remains the same; weight decreases E) 5.6/1.7^2 F) 5.7 m/s2 G) pentune H) mass remains the same; weight decreases

A) How does the gravity in the Space Shuttle compare with the gravity on Earth's surface? B) Why does the gravity in the Space Shuttle compare with the gravity on Earth the way it does? C) Why do the astronauts in the Space Shuttle float around?

A) The gravity in the Space Shuttle is approximately equal to the gravity on the surface of the Earth. B) The Space Shuttle and the surface of the Earth are about the same distance from the center of the Earth. C) The Space Shuttle is in free fall, so the shuttle and the astronauts inside it are continuously falling toward the Earth. They thus experience apparent weightlessness.

A) The following five diagrams show pairs of astronomical objects that are all separated by the same distance d. Assume the asteroids are all identical and relatively small, just a few kilometers across. Considering only the two objects shown in each pair, rank the strength, from strongest to weakest, of the gravitational force acting on the asteroid on the left.

A) sun, earth, moon, asteroid, atom

A) From the viewpoint of an observer in the orbiting rocket, what happens to time on the other rocket as it falls toward the event horizon of the black hole? B) As the falling rocket plunges toward the event horizon, an observer in the orbiting rocket would see that the falling rocket C) From Part B, you know that from afar you'll never see the in-falling rocket cross the event horizon, yet it will still eventually disappear from view. Why? D) If you were inside the rocket that falls toward the event horizon, you would notice your own clock to be running E) If you were inside the rocket that falls toward the event horizon, from your own viewpoint you would

A) time runs increasingly slower B) slows down as it approaches the event horizon and never actually crosses the event horizon C) Its light will become so redshifted that it will be undetectable. D) at a constant, normal rate as you approach the event horizon E) accelerate as you fall and cross the event horizon completely unhindered

Why are all tides greatest at the time of a full Moon or new Moon?

At full Moon and new Moon, the tides from the Moon and the Sun add because they are in line with Earth.

If the Moon pulls Earth as strongly as Earth pulls the Moon, why doesn't Earth rotate around the Moon, or why don't both rotate around a point midway between them?

Because the moon has a smaller mass than Earth and they have to rotate at a central point.

What was the cause of perturbations discovered in the orbit of the planet Uranus? What later discovery did this lead to?

Neptune caused the perturbations, and later Pluto was discovered.

What would be the path of the Moon if somehow all gravitational forces on it vanished to zero?

The Moon would move in a straight-line path instead of circling both the sun and earth.

Most people today know that the ocean tides are caused principally by the gravitational influence of the Moon, and most people therefore think that the gravitational pull of the Moon on Earth is greater than the gravitational pull of the Sun on Earth. What do you think?

The gravitational pull of the Sun on the Earth is greater than the gravitational pull of the Moon. The tides, however, are caused by the differences in gravitational forces by the Moon on opposite sides of the Earth. The difference in gravitational forces by the Moon on opposite sides of the Earth is greater than the corresponding difference in forces by the stronger pulling but much more distant Sun.

Where do you weigh more: at the bottom of Death Valley or atop one of the peaks of the Sierra Nevada? Why?

You weigh more in Death Valley because you are closer to the center of Earth

What would the magnitude of the gravitational field be anywhere inside a hollow, spherical planet?

Zero N/kg

Rank the microtidal forces on your own body, from greatest to least, produced by the following:

earth, sun, neptune

Find the change in the gravitational force between two planets if the masses of both planets are doubled but the distance between them stays the same.

f=4

If Earth shrank, but there was no change in its mass, then what would happen to your weight at the surface?

it would increase

The constant G in Newton's equation

makes the units of measurement consistent

A) Predict how the upward force exerted on the feet by the scale will compare to the weight of the man if the elevator is moving upward at a constant speed. B) Predict how the upward force exerted on the feet by the scale will compare to the man's weight if the elevator is moving downward at a constant speed. C) Predict how the upward force exerted on the feet by the scale will compare to the man's weight if the elevator is accelerating upward. D) Predict how the upward force exerted on the feet by the scale will compare to the man's weight if the elevator is accelerating downward.

A) The upward force on the feet will be equal to the man's weight. B) The upward force on the feet will be equal to the man's weight. C) The upward force on the feet will exceed the man's weight. D) The upward force on the feet will be less than the man's weight.

A) Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be B) Suppose you are in an elevator that is moving upward. As the elevator nears the floor at which you will get off, its speed slows down. During this time when the elevator is moving upward with decreasing speed, your weight will be C) As you found in Part A, your weight will be greater than normal when the elevator is moving upward with increasing speed. For what other motion would your weight also be greater than your normal weight? D) If you are standing on a scale in an elevator, what exactly does the scale measure?

A) greater than your normal weight at rest B) less than your normal weight at rest C) The elevator moves downward while slowing in speed. D) the force you exert on the scale