The speed of light in empty space, that is, a vacuum, is 300,000 km/s. The speed of sound in empty space is:
- B. greater than 0 but less than 300,000 km/s
- C. 300,000 km/s
- D. greater than 300,000 km/s
Correct Answer & Rationale
Correct Answer: A
The speed of sound requires a medium, such as air or water, to propagate; it cannot travel through a vacuum. Therefore, the speed of sound in empty space is effectively zero. Option B suggests that the speed of sound is greater than 0 but less than 300,000 km/s, which is incorrect because sound cannot exist in a vacuum. Option C states it is 300,000 km/s, which misrepresents sound's nature, as this speed is specific to light. Option D claims it is greater than 300,000 km/s, which is impossible since sound cannot travel in a vacuum at all. Thus, the only valid conclusion is that the speed of sound in empty space is zero.
The speed of sound requires a medium, such as air or water, to propagate; it cannot travel through a vacuum. Therefore, the speed of sound in empty space is effectively zero. Option B suggests that the speed of sound is greater than 0 but less than 300,000 km/s, which is incorrect because sound cannot exist in a vacuum. Option C states it is 300,000 km/s, which misrepresents sound's nature, as this speed is specific to light. Option D claims it is greater than 300,000 km/s, which is impossible since sound cannot travel in a vacuum at all. Thus, the only valid conclusion is that the speed of sound in empty space is zero.
Other Related Questions
Recycling will best benefit the environment by minimizing which THREE of the following?
- A. The consumption of raw materials
- B. The incineration of materials in combustion for energy
- C. The amount of materials in landfills
- D. The reuse of materials in new products
Correct Answer & Rationale
Correct Answer: A,B,C
Recycling effectively minimizes the consumption of raw materials (A) by reusing existing materials, reducing the need for new resource extraction. It also decreases the amount of materials sent to landfills (C), which helps mitigate environmental issues associated with waste accumulation. Additionally, recycling reduces the incineration of materials for energy (B), lowering greenhouse gas emissions and air pollution. Option D, the reuse of materials in new products, is not minimized by recycling; rather, recycling facilitates this process. Therefore, A, B, and C are the primary benefits of recycling for environmental protection.
Recycling effectively minimizes the consumption of raw materials (A) by reusing existing materials, reducing the need for new resource extraction. It also decreases the amount of materials sent to landfills (C), which helps mitigate environmental issues associated with waste accumulation. Additionally, recycling reduces the incineration of materials for energy (B), lowering greenhouse gas emissions and air pollution. Option D, the reuse of materials in new products, is not minimized by recycling; rather, recycling facilitates this process. Therefore, A, B, and C are the primary benefits of recycling for environmental protection.
An object is lifted above the floor to a height X, as illustrated, and then released. Which of the following best describes the object's energy?
- A. At height X, the energy is kinetic and changes to potential as the object falls.
- B. At height X, the energy is potential and changes to kinetic as the object falls.
- C. At height X, the energy is zero and the object gains both kinetic and potential energy as it falls.
- D. At height X, the energy is potential and the object gains kinetic energy as it falls, while its potential energy decreases.
Correct Answer & Rationale
Correct Answer: B
At height X, the object possesses gravitational potential energy due to its elevated position. As it falls, this potential energy is converted into kinetic energy, which increases as the object accelerates toward the ground. Option A is incorrect because at height X, the energy is primarily potential, not kinetic. Option C misrepresents the energy state; the energy is not zero at height X. Option D partially describes the process but does not clarify that the potential energy is transformed into kinetic energy, which is essential to understanding energy conservation during the fall.
At height X, the object possesses gravitational potential energy due to its elevated position. As it falls, this potential energy is converted into kinetic energy, which increases as the object accelerates toward the ground. Option A is incorrect because at height X, the energy is primarily potential, not kinetic. Option C misrepresents the energy state; the energy is not zero at height X. Option D partially describes the process but does not clarify that the potential energy is transformed into kinetic energy, which is essential to understanding energy conservation during the fall.
Of the following gases, which is found in the atmosphere in the greatest concentration?
- A. O2
- B. N2
- C. H2
- D. CO2
Correct Answer & Rationale
Correct Answer: B
Nitrogen (N2) constitutes about 78% of the Earth's atmosphere, making it the most abundant gas. Oxygen (O2), while essential for life, is present at around 21%, significantly less than nitrogen. Hydrogen (H2) is found in trace amounts and is not a major component of the atmosphere. Carbon dioxide (CO2) is also present in much smaller concentrations, approximately 0.04%, and is primarily significant for its role in climate regulation. Therefore, nitrogen is the predominant gas, while the others are present in much lower concentrations.
Nitrogen (N2) constitutes about 78% of the Earth's atmosphere, making it the most abundant gas. Oxygen (O2), while essential for life, is present at around 21%, significantly less than nitrogen. Hydrogen (H2) is found in trace amounts and is not a major component of the atmosphere. Carbon dioxide (CO2) is also present in much smaller concentrations, approximately 0.04%, and is primarily significant for its role in climate regulation. Therefore, nitrogen is the predominant gas, while the others are present in much lower concentrations.
Which THREE of the following are health problems associated with long-term exposure to air pollution?
- A. Accelerated aging of the lungs
- B. Increased lung capacity
- C. Increased risk of asthma
- D. Increased risk of cardiovascular disease
Correct Answer & Rationale
Correct Answer: A,C,D
Long-term exposure to air pollution can lead to several significant health issues. Option A, accelerated aging of the lungs, is accurate as pollutants can damage lung tissue over time, reducing function. Option C is also correct; exposure to air pollution is linked to a higher incidence of asthma, particularly in children, due to airway inflammation and increased sensitivity. Option D is valid as well; numerous studies show that air pollution significantly raises the risk of cardiovascular diseases due to systemic inflammation and oxidative stress. Conversely, Option B, increased lung capacity, is incorrect. Air pollution typically impairs lung function rather than enhancing it, leading to reduced capacity over time.
Long-term exposure to air pollution can lead to several significant health issues. Option A, accelerated aging of the lungs, is accurate as pollutants can damage lung tissue over time, reducing function. Option C is also correct; exposure to air pollution is linked to a higher incidence of asthma, particularly in children, due to airway inflammation and increased sensitivity. Option D is valid as well; numerous studies show that air pollution significantly raises the risk of cardiovascular diseases due to systemic inflammation and oxidative stress. Conversely, Option B, increased lung capacity, is incorrect. Air pollution typically impairs lung function rather than enhancing it, leading to reduced capacity over time.