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# Magnitudes and Scale

How do we represent really big numbers?

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State the approximate value of the following quantities in SI units to the nearest order of magnitude.  The first two have been answered for you as examples.

1) Length of a day

SI unit for time = second.  1 hour = 60 mins, 1 min = 60 seconds so 24 hours = 86400 seconds = 8.64 x 104 seconds.

2) Mass of a bus

If we say a bus is approximately 2 tons, 2 tons is 2000kg (kg is the SI unit for mass)

= 2 x 103 kg

## REMEMBER - your answer must be in SI units and standard form!

3) If an average person has a mass of 60kg, and the world population is currently around 7 billion people, estimate the mass of the human race.

4) The size of a microbe (the clue is in the name!).

5) The energy in a snack of your choice.

6) The width of your hand.

7) The height of a door.

8) The width of your thumb nail.

9) The number of seconds you have been calculating these answers!

10) Your age (yes it is constantly changing but this is an estimate...)