Different types of light bulbs use different amounts of electricity. Electricity use is measured in kilowatt hours (kWh). The electricity use per hour (kWh) of an electrical device can be calculated using the following equation:
A 60W light bulb used .48 kilowatt hours of electricity. How long was the light bulb on?
- A. 0.48 hours
- B. 28.8 hours
- C. 0.125 hours
- D. 8 hours
Correct Answer & Rationale
Correct Answer: D
To determine how long the 60W light bulb was on, we first convert the energy used from kilowatt hours to watt hours: 0.48 kWh equals 480 watt hours. Using the formula: time (hours) = energy (watt hours) / power (watts), we calculate: 480 watt hours / 60 watts = 8 hours. Option A (0.48 hours) underestimates the time significantly. Option B (28.8 hours) incorrectly suggests the bulb was on much longer than the energy consumed allows. Option C (0.125 hours) miscalculates by assuming a much higher power consumption. Only option D accurately reflects the time the bulb was on based on the energy used.
To determine how long the 60W light bulb was on, we first convert the energy used from kilowatt hours to watt hours: 0.48 kWh equals 480 watt hours. Using the formula: time (hours) = energy (watt hours) / power (watts), we calculate: 480 watt hours / 60 watts = 8 hours. Option A (0.48 hours) underestimates the time significantly. Option B (28.8 hours) incorrectly suggests the bulb was on much longer than the energy consumed allows. Option C (0.125 hours) miscalculates by assuming a much higher power consumption. Only option D accurately reflects the time the bulb was on based on the energy used.
Other Related Questions
Scientists are Interested in whether certain greenhouse gases have helped cause I recent temperature increases. The graph presents data on carbon dioxide and methane gas levels in the atmosphere for the past several centuries. Human activities began producing large quantities of both gases in the 1700s. This graph, combined with information from--------------------, supports ----------------------.
- A. The Milankovitch climate change model
- B. paragraph 3
- C. The anthropogenic climate change model
- D. Paragraph 2
Correct Answer & Rationale
Correct Answer: B, C
The graph illustrates the correlation between rising greenhouse gas levels and temperature increases, supporting the anthropogenic climate change model, which attributes climate change to human activities. Options B and C effectively connect the visual data with the broader context of human influence on climate. Option A, referencing the Milankovitch model, is incorrect as this model focuses on natural Earth cycles, not human impact. Option D lacks specificity and does not directly relate to the evidence presented in the graph. Thus, B and C provide the most relevant support for understanding the relationship between greenhouse gas emissions and climate change.
The graph illustrates the correlation between rising greenhouse gas levels and temperature increases, supporting the anthropogenic climate change model, which attributes climate change to human activities. Options B and C effectively connect the visual data with the broader context of human influence on climate. Option A, referencing the Milankovitch model, is incorrect as this model focuses on natural Earth cycles, not human impact. Option D lacks specificity and does not directly relate to the evidence presented in the graph. Thus, B and C provide the most relevant support for understanding the relationship between greenhouse gas emissions and climate change.
Which statement from the passage refutes Lavoisier's idea that heat is a fluid that leaves a hot substance and travels to a colder substance?
- A. He also found the brass filings produced from the drilling process contained enough heat to boil water while retaining their weight.
- B. James Joule discovered that heat could be produced by moving a wire through a magnetic field.
- C. Lavoisier demonstrated that oxygen was required for combustion.
- D. Count Rumford observed that the process of boring out cannons from brass cylinders continuously produced heat.
Correct Answer & Rationale
Correct Answer: A
Option A effectively refutes Lavoisier's notion of heat as a fluid by demonstrating that heat can be generated without the transfer of a fluid. The brass filings, despite retaining their weight, produced sufficient heat to boil water, indicating that heat can arise from mechanical processes rather than fluid movement. Option B, while highlighting Joule's discovery of heat production through motion, does not directly address Lavoisier's fluid concept. Option C focuses on combustion and oxygen's role, which is unrelated to the nature of heat itself. Option D describes an observation of heat generation during a mechanical process but does not emphasize the implications for Lavoisier's fluid theory as clearly as A does.
Option A effectively refutes Lavoisier's notion of heat as a fluid by demonstrating that heat can be generated without the transfer of a fluid. The brass filings, despite retaining their weight, produced sufficient heat to boil water, indicating that heat can arise from mechanical processes rather than fluid movement. Option B, while highlighting Joule's discovery of heat production through motion, does not directly address Lavoisier's fluid concept. Option C focuses on combustion and oxygen's role, which is unrelated to the nature of heat itself. Option D describes an observation of heat generation during a mechanical process but does not emphasize the implications for Lavoisier's fluid theory as clearly as A does.
Which statement describes a weakness of the investigation in the passage?
- A. None of the hypotheses are directly related to the ice core data.
- B. The Greenland ice sheet is far away from the site of the explosion in Russia.
- C. Several of the hypotheses rely on unproven processes or estimated values.
- D. A few micrograms of ammonia is insufficient evidence for a conclusion.
Correct Answer & Rationale
Correct Answer: C
Option C highlights a significant weakness, as relying on unproven processes or estimated values can lead to unreliable conclusions, undermining the investigation's credibility. Option A is incorrect because hypotheses can be related to data in broader contexts, even if not directly. Option B misrepresents the geographical relevance; distance alone does not invalidate the connection between the ice core data and the explosion. Option D, while suggesting a concern about evidence quantity, does not address the fundamental issue of reliance on unproven processes that can skew the investigation's outcomes.
Option C highlights a significant weakness, as relying on unproven processes or estimated values can lead to unreliable conclusions, undermining the investigation's credibility. Option A is incorrect because hypotheses can be related to data in broader contexts, even if not directly. Option B misrepresents the geographical relevance; distance alone does not invalidate the connection between the ice core data and the explosion. Option D, while suggesting a concern about evidence quantity, does not address the fundamental issue of reliance on unproven processes that can skew the investigation's outcomes.
The roller coaster diagram shows a set of cars moving downward from position 1 to position 2. As the cars travel from position 1 toward position 2, their...
- A. gravitational potential energy; total energy
- B. kinetic energy; gravitational potential energy
- C. total energy; kinetic energy
- D. gravitational potential energy; kinetic energy
Correct Answer & Rationale
Correct Answer: A
As the roller coaster cars move from position 1 to position 2, they descend, resulting in a decrease in gravitational potential energy due to their lower height. However, their total energy—comprising both kinetic and potential energy—remains constant, assuming negligible friction. Option B incorrectly suggests that kinetic energy increases while gravitational potential energy decreases, but it does not address total energy. Option C misrepresents the relationship by stating total energy changes, which it does not. Option D also fails, as it inaccurately implies that gravitational potential energy is the only energy type being discussed.
As the roller coaster cars move from position 1 to position 2, they descend, resulting in a decrease in gravitational potential energy due to their lower height. However, their total energy—comprising both kinetic and potential energy—remains constant, assuming negligible friction. Option B incorrectly suggests that kinetic energy increases while gravitational potential energy decreases, but it does not address total energy. Option C misrepresents the relationship by stating total energy changes, which it does not. Option D also fails, as it inaccurately implies that gravitational potential energy is the only energy type being discussed.