A student has been asked the following question:A 2.5 kW cement mixer provides 50 kJ of work mixing the raw materials.Calculate the time the cement mixer was on for.They carried out their calculation using the following steps:P = 2 kW = 2000 WW = 50 kJ = 50 000 JP = W / t2000 = 50 000 / t2000 x t = 50 000t = 50 000 / 2000t = 25 secondsHas this been answered correctly?This has been calculated correctly, but they used incorrect units.They did not convert kilowatts into watts.They made an error when rearranging the equation.This has been calculated and answered correctly.This has been calculated incorrectly due to misreading the numbers in the question.

A student has been asked the following question:Calculate the work done when an elevator with a power rating of 3 kW ascends for 25 seconds.They carried out their calculation using the following steps:P = 3 kW = 3000 Wt = 25 secondsP = W / t3000 = W / 25W = 3000 x 25W = 75 000 J = 75 kJHas this been answered correctly?They did not convert kilowatts into watts.There was an error in the calculation on one of the lines of working.This has been calculated correctly, but they have used incorrect units in the final answer.This has been calculated incorrectly due to misreading the numbers in the question.This has been calculated and answered correctly.

A student has been asked the following question:Calculate the energy transferred when an elevator with a power rating of 4 kW ascends for 2 minutes.They carried out their calculation using the following steps:P = 4 kW = 4000 Wt = 2 minutesP = E / t4000 = E / 2E = 4000 x 2E = 8000 JHas this been answered correctly?No, they did not rearrange the equation correctly.Yes, they have calculated this correctly.No, they forgot to convert the kilowatts into watts to use in the calculation.No, they did not convert time into seconds.No, they have given their answer in joules when it should be in kilojoules

Power = 3 kWWork done = 825 kJCalculate the time.Time = _____ s

Energy transferred = 3200 joulesTime = 160 secondsCalculate the power, you must include units in your answer.

16. Calculate the time it takes a 0.5 kW appliance to transfer 1.3 kJ of energy (1dp)