Chapter 9 MP (Extra Credit)

After the discovery of Uranus, astronomers calculated its orbit and predicted its position in the sky using Kepler's laws of planetary motion, which had been known since the early 17th century. However, they soon discovered a small discrepancy between the predicted and actual positions of Uranus. As a scientist, what should you do when presented with such a conflict between prediction and observation?

*All of these: think about what else might cause the observed discrepancy, consider whether Kepler's laws need to be modified to account for the new observations, verify that your observations are correct, consider that Uranus may not be a planet

Which of the following quantities represent mass?

0.34 g, 120 kg

Which of the following quantities would be acceptable representations of weight?

12.0 lbs, 1600 kN, 899 MN

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.

Pentune

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 __________.

greater than your normal weight at rest

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 __________.

less than your normal weight at rest

As the falling rocket plunges toward the event horizon, an observer in the orbiting rocket would see that the falling rocket __________.

slows down as it approaches the event horizon, and never actually crosses the event horizon Viewed from afar, time comes to a stop at the event horizon of a black hole, so falling objects never appear to cross the event horizon.

If you are standing on a scale in an elevator, what exactly does the scale measure?

the force you exert on the scale

If the acceleration due to gravity on the earth is 9.8 m/s2m/s2, what is the acceleration due to gravity on Rams?

5.7 m/s2m/s2

From Part B, you know that from afar we'll never see the in-falling rocket cross the event horizon, yet it will still eventually disappear from view. Why?

Its light will become so redshifted that it will be undetectable. As the animation shows, viewed from afar the light of the in-falling rocket becomes increasingly redshifted. As it approaches the event horizon, the redshift approaches infinity, meaning all its light is stretched to such enormous wavelengths that no detector could see it, even in principle.

Why does the gravity in the Space Shuttle compare with the gravity on Earth the way it does?

The Space Shuttle and the surface of the Earth are about the same distance from the center of the Earth.

Why do the astronauts in the Space Shuttle float around?

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.

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?

The elevator moves downward while slowing in speed.

How does the gravity in the Space Shuttle compare with the gravity on Earth's surface?

The gravity in the Space Shuttle is approximately equal to the gravity on the surface of the Earth

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.

The upward force on the feet will be equal to the man's weight.

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.

The upward force on the feet will be equal to the man's weight.

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

The upward force on the feet will be less than the man's weight.

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.

The upward force on the feet will exceed the man's weight.

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?

Time runs increasingly slower as the rocket approaches the black hole. In this animation, our view is similar to the view from the orbiting rocket. Notice that the clock on the falling rocket ticks more slowly as it approaches the black hole, indicating that time is slowing down.

If you were inside the rocket that falls toward the event horizon, from your own viewpoint you would __________.

accelerate as you fall and cross the event horizon completely unhindered From your point of view, time runs normally in your spaceship and gravity must accelerate you as you fall toward the black hole. There is no physical barrier at the event horizon, so you cross it unhindered.

If you were inside the rocket that falls toward the event horizon, you would notice your own clock to be running __________.

at a constant, normal rate as you approach the event horizon All motion is relative, and you will always consider your own clock to be running at a normal rate.

If acceleration due to gravity on the earth is g which formula gives the acceleration due to gravity on Loput?

g5.61 over 1.7(2 squared)

After Punch Taut travels to Pentune, what actually happens to his mass and his weight?

mass remains the same; weight decreases

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 remains the same; weight decreases

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?

weight only