Question 1: Define power in the context of energy transfer, including its SI unit.

Answer: Power is the rate at which work is done or energy is transferred, measured in watts (W).

Question 2: Explain how power differs from energy.

Answer: Energy is the total amount of work done or heat transferred, while power is the rate at which this work or transfer occurs.

Question 3: Calculate the power used if a motor does 300 joules of work in 10 seconds.

Answer: Power = Work / Time = 300 J / 10 s = 30 W

Question 4: A car engine produces 150 kilowatts of power. How much work does it do in 2 hours? (Show your calculation and answer in joules.)

Answer: Work = Power × Time = 150,000 W × 7200 s = 1,080,000,000 J

Question 5: Name a device or machine where high power output is essential, and explain why.

Answer: A jet engine; high power is essential to generate enough thrust for flight.

Question 6: Identify the variables that affect the power output of a machine.

Answer: The variables include the amount of work done and the time taken to do that work.

Question 7: Describe a safety precaution to consider when working with high-power electrical devices.

Answer: Ensure proper insulation and avoid overloading circuits to prevent electrical fires or shocks.

Question 8: A worker lifts a box weighing 50 kg to a height of 2 meters in 4 seconds. Calculate the power exerted during this activity. (Use g = 9.8 m/s²).

Answer: Work = m × g × h = 50 kg × 9.8 m/s² × 2 m = 980 J Power = Work / Time = 980 J / 4 s = 245 W

Question 9: In an industrial setting, machines are rated based on their power output. Why is this rating important for safety and efficiency?

Answer: It helps ensure machines are operated within safe limits and run efficiently without overload or damage.

Question 10: Explain how increasing the time taken to do the same amount of work affects the power output.

Answer: Increasing the time decreases the power output because power is inversely proportional to time for a given amount of work.

Question 11: Describe a real-world application where controlling power output is critical for safety or performance.

Answer: In electric vehicles, controlling the power output is critical to ensure safe acceleration, prevent overheating of batteries, and optimize energy efficiency during driving.