Question 1: Define 'power' in the context of physics and describe its units of measurement.

Answer: Power is the rate at which energy is transferred or converted; its SI unit is the watt (W), which equals one joule per second (J/s).

Question 2: Explain how increasing the time taken for an energy transfer affects the power output, assuming the energy transferred remains constant.

Answer: Increasing the time taken for a transfer decreases the power output because power is inversely proportional to time for a given amount of energy transferred.

Question 3: Calculate the power used when 1500 joules of energy are transferred in 30 seconds.

Answer: Power = Energy transferred / Time = 1500 J / 30 s = 50 W

Question 4: A motor does 600 joules of work in 20 seconds. What is its power output?

Answer: Power = 600 J / 20 s = 30 W

Question 5: Multiple Choice: Which of the following statements is true about power?

Answer: Power is the rate at which energy is transferred or converted.

Question 6: Fill in the blank: The SI unit of power is the __________.

Answer: watt

Question 7: Describe a practical scenario where increasing the power of a machine could improve its efficiency. Include at least two factors that could be affected.

Answer: Increasing the power of a machine, such as a conveyor belt, can improve efficiency by transferring more energy in less time, reducing operation time and increasing throughput. Factors affected include energy consumption rate and overall productivity.

Question 8: Identify three safety precautions that should be considered when operating high-power electrical equipment.

Answer: Ensure proper insulation and grounding, avoid overloading circuits, and follow manufacturer safety guidelines.

Question 9: A 2 kW electric heater is used for 5 hours per day. Calculate the total energy consumed in kilowatt-hours (kWh).

Answer: Energy = Power × Time = 2 kW × 5 hours = 10 kWh

Question 10: Data Analysis: A vehicle engine transfers 100,000 joules of energy over 2 hours of operation. Calculate the average power output in watts and interpret what this indicates about the engine's performance.

Answer: Power = 100,000 J / (2 hours × 3600 s/hour) = 100,000 J / 7200 s ≈ 13.89 W. This indicates a very low average power, typical of a small or idle engine, or an example scenario for understanding energy transfer over time.

Question 11: Explain why a more powerful laser can cut through thicker material compared to a less powerful laser, considering the concept of power.

Answer: A more powerful laser delivers a higher rate of energy transfer (higher power), enabling it to generate more heat and energy concentration in a shorter period. This allows the laser to cut through thicker material more effectively than a less powerful laser, which transfers energy at a slower rate.