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Scale Drawings. To understands what scale drawings are. To be able to draw scale drawings To understand scale drawings. What are scale drawings? Scale drawings are everywhere!. Scale Drawings. On Maps. Vehicle design. Footprints of houses. Can you think of any more?.
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Scale Drawings To understands what scale drawings are. To be able to draw scale drawings To understand scale drawings.
What are scale drawings? Scale drawings are everywhere! Scale Drawings On Maps Vehicle design Footprints of houses Can you think of any more?
Scale drawings are SIMILAR to the original. To say that two objects are SIMILAR means that they are identical in shape, but not in size. In order for two shapes to be similar they must have the same angles and the sides must be in the same ratio. Example: Are these two shapes similar? x2 Angles the same x2 The two shapes are similar x2 Sides have the same ratio – x2 x2
Are these pairs of shapes similar? 6cm 2cm 3cm 9cm 50° 50° 4m 6m 40° 5m 40° 10m 1m 70° 1.5m 50° 2m 60° 3m
Understanding scales All scale drawings must have a scale written on them. Scales are usually expressed as ratios. Normally for maps and buildings the ratio: Drawing length: Actual length For maps the ratio is normally in the ratio: Map distance: Actual Distance Example: 1cm : 100cm The ratio 1cm:100cm means that for every 1cm on the scale drawing the length will be 100cm in real life Example: 1:10000 The ratio 1:10000 means that the real distance is 10000 times the length of one unit on the map or drawing.
Writing scale ratios When you write a scale you must make sure that the units are the same. Example Simplify the scale 5cm to 1m 5cm:1m 5cm:100cm 1cm:20cm Convert to the same units All ratios must be in the form 1:n. To make cm 1cm then we must divide each side by 5 • Questions – Simplify the following scales • 10cm: 2m • 5mm:10cm • 1cm:1km 1cm:20cm 1mm:20mm 1cm:100000cm
Making a scale drawing • Task • Make a scale drawing of the building which you are renovating. To do this you need to measure EVERY room and the outside of the building. Do this in metres. • After you have measured the building you need to decide on a scale. Remember the whole drawing needs to fit on an A3 piece of paper. • (I advise you use the scale 1cm:100cm) • Using the scale 1cm:100cm • If a rectangular room measures 2.5m by 4m then you have to convert both of the lengths into cm. (as this is the unit in the scale) • 2.5m = 250cm, 4m = 400cm • If 100cm in the actual drawing is represented by 1cm then to get from the actual to the scale you need to divide by 100. • 250cm ÷ 100 = 2.5cm 400cm ÷ 100 = 4cm • On the scale drawing this room would be 2.5cm by 4cm