1.1 Estimating worksheet PDF

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1.1 Estimating approximate sizes and values It is always useful to be able to estimate the size of a quantity. An important phrase here is “the right order of magnitude”. This means getting the number to the nearest power of 10. For example, a table has a mass of around 20 kg, not 200 kg. To the nearest order of magnitude this is 101 kg. Estimation problems – Estimate the following quantities, THEN (after you have done all the estimates) measure or find out the quantities. Fill in the remaining columns. Actual order of magnitude . 10^1

Good estimate? (Yes or no)

5*10^2 m

10^3

Yes

10^2 K

3.02*10^2K

10^2

Yes

10^2 K

2.98x10^2 K

10^K

Yes

10^2 m3

9.3x10^2

10^2

Yes

10^25 kg

5.983x10^24 kg

10^25

Yes

Quantity

Estimate (to the nearest power of 10). Include unit.

Actual value

The mass of a ball point pen. Mr Sumner`s mass. The distance from the classroom door to the IT room. The temperature outside. The room temperature. The volume of the room. Mass of the Earth.

10^1g

10^1 g

10^2 kg

8.4x10^1

10^3 m

Yes

Here are some harder estimates! Don`t just guess, but try to justify your estimates (show your working on the back of the page). Estimate: 1. The time it would take (in years) to reach the sun in an aeroplane (distance 1.5 x 108 km). - 900km/h -> 900 x 24 x 365 = 7,884,000 km per year - 1.5 x 108 / 7.884 x 106 = 1.902587519 x 101 ≅ 19 years 2. The speed that grass grows during the summer (in m.s-1) - Grass grows around 4 inches a month - Summer is two months, so 8 inches, which is 2 x 10-1 m 3. The number of classrooms that the amount of faeces (poo!) excreted by everyone in the world per day (population of earth = 7,000,000,000) would fill. - 0.000414 x 7,000,000,000 = 2898000 m3 - Average classroom is 125 m3 - 2898000 m3/ 125 m3 = 23,184 4. The number of heartbeats you have in your life. - 70 (60 x 60 x 24 x 365) = 2,207,520,000 5. Think up an interesting “estimate” of your own....