Here is the solution to the physics question: 1. A washing machine is marked 240 V, 3 kW. What does this mean? Hence calculate the electrical energy used up by this machine in 1 hour. Meaning of the markings: 240 V: This indicates the rated voltage or operating voltage* of the washing machine. It means the machine is designed to operate safely and efficiently when connected to a 240-volt electrical supply. 3 kW: This indicates the rated power* of the washing machine. It means the machine consumes electrical energy at a rate of 3 kilowatts when it is operating at its normal capacity under the rated voltage. Calculation of electrical energy used: Step 1: Identify the given values. The power of the washing machine is $P = 3 \text{ kW}$. The time for which the machine operates is $t = 1 \text{ hour}$. Step 2: Use the formula for electrical energy. Electrical energy ($E$) is calculated as the product of power ($P$) and time ($t$). $$E = P \times t$$ Step 3: Substitute the values into the formula and calculate. $$E = 3 \text{ kW} \times 1 \text{ hour}$$ $$E = 3 \text{ kWh}$$ The electrical energy used up by this machine in 1 hour is $\boxed{\text{3 kWh}}$.