Question 1: Define power in the context of physics.

Answer: Power is the rate at which work is done or energy is transferred over time.

Question 2: Explain how power relates to energy transfer and time.

Answer: Power relates to energy transfer and time through the formula power = energy transferred / time taken.

Question 1: A motor transfers 1500 Joules of energy in 30 seconds. Calculate its power output in Watts.

Answer: 50 Watts

Question 2: A cyclist does 600 Joules of work in 2 minutes. What is the average power output in Watts?

Answer: 5 Watts

Question 3: If a machine has a power of 250 Watts and operates for 4 hours, how much energy does it transfer in Joules?

Answer: 3,600,000 Joules

Question 1: Describe a simple experiment to measure the power of a light bulb. Include the variables you would measure and safety precautions.

Answer: To measure the power of a light bulb, connect it to a power supply and measure the voltage across and current through the bulb using a voltmeter and ammeter. Calculate the power using P = V × I. Variables include voltage, current, and time. Safety precautions include ensuring the power supply is turned off before connecting or disconnecting the circuit, and avoiding contact with live electrical components.

Question 1: A washing machine has a power rating of 2 kW and is used for 1 hour. How much energy does it transfer? Express your answer in Joules.

Answer: 7,200,000 Joules

Question 2: In a factory, a conveyor belt operates with a power of 5 kW. If it runs for 8 hours, how much energy is transferred during this period?

Answer: 144,000,000 Joules

Question 1: A car engine produces 150 kW of power. If it operates for 2 hours, how much energy in kilowatt-hours does it transfer? Show your working.

Answer: 0.3 kilowatt-hours

Question 2: Explain why understanding power is important in designing energy-efficient appliances.

Answer: Understanding power helps engineers design appliances that transfer energy effectively without wasting excess energy, thereby reducing energy consumption and operational costs. It also ensures appliances operate within safe power limits, preventing overheating and damage.

Question 1: Describe how power ratings are used when selecting household electrical appliances, and why it is important.

Answer: Power ratings indicate how much energy an appliance uses per second, helping consumers choose efficient devices and ensuring the electrical system can supply the required power safely.