NEWTONS LAW OF GRAVITATION-KEPLER'S LAW-SHM+MECHANICAL(80PTS))

What is the cause of "weightlessness" for an astronaut in orbit?

• A. The astronaut is in a location where there is no gravitational force.

• B. The astronaut is moving at a speed that counteracts gravity.

• C. The astronaut is in free-fall, accelerating with the acceleration due to gravity.

• D. The astronaut's body is too far from Earth for gravity to have any effect.

Answer explanation

• Correct Answer: C.
  
  
  The text explains that there is no "zero gravity" in orbit and that weightlessness is simply the experience of being in free-fall.

According to the text, what is a negative effect of extended time in microgravity on astronauts?

• A. decrease bone mass.

• B. Muscle atrophy.

• C. Improved immune system function.

• D. decrease appetite.

Answer explanation

Correct Answer: B.

The text explicitly states that "muscles will atrophy (waste away) in this environment" and that there is a "corresponding loss of bone mass."

What is a positive finding from space research?

• A. Plants can grow without a need for water.

• B. Bacteria grow more slowly in microgravity.

• C. Microbial antibiotic production can increase in space-grown cultures.

• D. Astronauts' hearts become stronger in microgravity.

Answer explanation

Correct Answer: C.

The text notes that "studies indicate that microbial antibiotic production can increase by a factor of two in space-grown cultures."

What was a significant outcome of the Cavendish experiment?

• A. It was used to prove that the Earth is a sphere.

• B. It allowed for the first accurate calculation of Earth's mass.

• C. It proved that gravity is the strongest of the four fundamental forces.

• D. It showed that the gravitational force depends on the substance.

Answer explanation

Correct Answer: B.

The text states that "One important consequence of knowing G was that an accurate value for Earth’s mass could finally be obtained."

What can a black hole's tidal forces do to a companion star?

• A. They can cause the star to expand.

• B. They can make the star move away.

• C. They can tear matter from the star.

• D. They can increase the star's temperature.

Answer explanation

Correct Answer: C.

The text says that the tidal forces near black holes are "so great that they can actually tear matter from a companion star."

Based on the text, what is the most accurate description of the relationship between gravity and blood pressure on Earth?

• A. Gravity causes blood pressure to be higher in the head than the feet.

• B. The absence of gravity in orbit increases blood pressure in the feet.

• C. Gravity exerts a downward force on the column of blood, leading to higher pressure in the feet.

• D. The cardiovascular system is unaffected by gravity, so there is no pressure differential.

Answer explanation

Correct Answer: C.

The text states that blood pressure is "usually higher in the feet than in the head, because the higher column of blood exerts a downward force on it, due to gravity."

Which statement about the Cavendish experiment's difficulty is best supported by the provided text?

• A. The experiment was difficult because it was the first time anyone had measured gravitational force.

• B. The experiment was challenging due to the need to measure the tiny gravitational attraction between ordinary-sized masses.

• C. The experiment was difficult because it took over 100 years after Newton to develop the necessary technology.

• D. The experiment was difficult because it was conducted in a microgravity environment.

Answer explanation

Correct Answer: B.

The text states that Cavendish's experiment was "very difficult because he measured the tiny gravitational attraction between two ordinary-sized masses."

According to the text, what did Roland von Eötvös's experiments with gravity conclude?

• A. The gravitational force depends on the density of the substance.

• B. The gravitational force is identical for equal masses of different substances.

• C. The gravitational force is stronger for lead than for water.

• D. The gravitational force is identical over sub-millimeter distances.

Answer explanation

Correct Answer: B.

The text states that Eötvös found that "the gravitational force does not depend on the substance," which means a kilogram of lead would exert the same pull as a kilogram of water.

How does the text link the study of crystals in microgravity to clinical medicine on Earth?

• A. The high-quality crystals grown in space can be used as new medical instruments.

• B. Studying the structure of high-quality crystals can lead to better results for crystallography, which may have clinical importance.

• C. Growing crystals in microgravity can improve the immune system of astronauts.

• D. The improved crystals can be used to treat cardiovascular diseases.

Answer explanation

• Correct Answer: B.
  
  The text notes that high-quality crystals grown in space allow for "crystallography studies on their structure [that] can yield much better results," and earlier in the paragraph, it links findings in space to "clinically important" knowledge for managing diseases on Earth.

The text suggests a potential future use for plants in long-duration space missions. What is this use?

• A. As a source of oxygen for the crew's food.

• B. To provide a life support system by regenerating the atmosphere, purifying water, and producing food.

• C. To provide a life support system by producing more high-quality protein crystals.

• D. To provide a life support system by increasing antibiotic production.

Answer explanation

Correct Answer: B.

The text states that plants "might be able to provide a life support system for long duration space missions by regenerating the atmosphere, purifying water, and producing food."