A force of 13.8 N was used to lift a mass 30 cm vertically through a liquid. Calculate the work done in lifting the mass, stating the correct units.

Either from memory or using the formula booklet provided we know Work Done = Force x Distance Moved (in the direction of the force). Therefore we can use the values given and this formula to workout our answer. Before plugging in our values we should always double check they are in the correct S.I. units. 13.8N is correct (Force is measured in N) however 30cm is incorrect as Distance/Length is always measure in M, therefore we need to convert this value into M before using it in our formula. 30cm = 0.3m, you can work this out a number of different ways but the easiest would probably be to remember there's 100cm in 1m, so we can do (30/100) x 1 to get our value for 30cm in m. Now we just put our values into the equation: Work Done = 13.8 x 0.3 = 4.14 with the unit Joules (J) = 4.14J. (Work done is the amount of energy transferred in moving the mass so the unit is Joules ~ J).