| A conversion factor is a number used to change one set of units to another, by multiplying or dividing. |
Calculated Volume to Liquid Volume Conversions
In the everyday life when we think of volume, we associate it with litres (l) but when the volume is calculated it is in cubic units (cm3, mm3, and m3).
Conversions between these two formats will always be given.
Liquid volume conversions cheat sheet.
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Liquid Volume Conversions |
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1 cm3 |
1 ml |
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1 l |
1 000 ml |
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1 m3 |
1 kl |
EXAMPLES:
- A container that is roughly in the shape of a rectangular box. Has the following dimensions:
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Therefore, its volume |
= |
l × w × h |
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= |
10 cm × 10 cm × 5 cm |
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= |
500 cm3 |
Using the conversions 1 cm3 = 1 ml and 1 000 ml = 1 l:
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From the cheat table: 1 cm3 = 1ml 1000ml = 1l Therefore, 5 000 000 cm3 = 5 000 000 ml To convert millilitre (ml) to litre (l) divide by 1 000. Therefore,
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| 5 000 000 cm3 = 5 000l |
Calculated Area to Liquid Volume Conversions
Area is calculated in square units (cm2, mm2, m2). This type of conversion is normally used to calculate the volume of liquid needed to cover a specific area or surface, to calculate this the spread rate is needed. This tells us how much area a litre of paint (or other liquid) can cover. The spread rate will always be given (e.g., 5 m2 per litre).
The spread rate depends on:
- The type and thickness of the paint (or other liquid).
- The texture (roughness) of the surface to be covered.
- How absorptive the surface to be covered is.
EXAMPLE:
A weed pesticide states that it requires 80 ml of concentrate for 100 m2 of land area. What volume of pesticide will be required to treat the area?
Land area to be treated with weed pesticide
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Area |
= length × breadth |
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| = 30 m × 10 m | ||
| = 300 m2 | ||
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Pesticide required = |
80 ml : 100 m2 |
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(÷ 100; x 300) |
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240 ml: 300 m |
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| weeeeeeeeeeeeeeee | ||
Another pesticide states that it requires 50 ml of concentrate for 120 m2 of land area. What volume of pesticide will be required to treat the area?
Land area to be treated with second weed pesticide
| Area |
= length × breadth |
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| = 40 m × 15 m | |||
| = 600 m2 | |||
| Pesticide required = |
50 ml : 120 m2 |
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(÷ 120; x 600) |
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250 ml: 600 m |
Other Useful Building Conversions
The ratios are always given and they can be given in two ways:
- Visually
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Cement |
Concrete sand |
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 |
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1 bag |
1⅟₄ wheelbarrows |
1⅟₄ wheelbarrows |
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To make 1 cubic m of concrete you will need 7.7 bags of cement, 0.62 cubic metres of sand, and 0.62 cubic metres of stone. |
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- In a ratio.
Building material ratios
- Both representations show the same ratio. However, the visual one is easier to access for large volumes where a builder is using a wheelbarrow (e.g. pouring concrete for a floor), while the number ratio is for smaller volumes (e.g. pouring concrete for a small step).
EXAMPLE:
Using the ratios in the Figures above, how much stone will be required to mix with half a bag of cement? (Note: 1 bag of cement has a volume of 35 litres.)
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Using the pictorial version: |
1 bag mixes with 1 wheelbarrow of stone. |
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So, 1 bag mixes with 1.25 wheelbarrows of stone. |
| So a 0.5 bag will need 0.5 × 1,25 = 0,625 wheelbarrows of stone. |
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Using the ratio version: |
1 part of cement mixes with 2.5 parts of the stone. |
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0.5 bag of cement = 0.5 × 35 litres = 17.5 litres of cement. |
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17.5 litres cement will need 17,5 × 2,5 = 43.75 litres stone. |
Which is better?
0,625 wheelbarrows seem a rather difficult amount to measure. However, a normal bucket often holds about 5 l. So, 43.75 l is approximately 9 buckets in volume.
For smaller amounts, it seems better to use the ratio; however, if there were 4 bags of cement it would be much faster to measure the sand and stone with a wheelbarrow!