## 5. Self assessment:

Try the following self-assessment questions. Each statement is either completely correct or completely incorrect, even where there is more than one fact in the statement. When you have decided on your answer, mouse over the answer button to check:

• A length of one metre is written as 1 m and a length of two metres is written as 2 ms.

• The symbol km2 represents an area of one thousand square metres.

• The expression 5 m s-1 is the correct way to write a speed of five metres per second, and 5 m/s is incorrect.

• A clock frequency for a computer processor of 4 GHz means that the clock runs at four thousand million cycles per second.

• Weight and mass are the same thing.

• An energy transfer of 1 kW means one thousand joules transferred per second (1 kJ s-1).

• The Celsius degree, °C, is defined as one hundreth of the difference in temperature between the freezing point and boiling point of water.

• The freezing point of water is 32°C.

• A force is mass multiplied by acceleration. It has the derived unit of the newton (N), where 1 N = 1 kg m s-2.

• One picometre (pm) is equal to one thousand nanometres (nm).

• There are one thousand kilogrammes in a metric tonne, so 1 tonne = 1 Mg (megagramme).