Grade 10 power mechanics – Scales Quiz
1. In technical drawing for power mechanics, what does a scale of 1:10 mean?
A scale written 1:10 means the drawing is reduced; 1 unit on paper equals 10 units in real life (e.g., 1 cm on paper = 10 cm on the object).
2. A machine part measures 2.4 m in reality. If it is drawn at a scale of 1:20, what is its length on the drawing in millimetres?
Scale 1:20 means drawing length = actual length ÷ 20. 2.4 m = 2400 mm; 2400 ÷ 20 = 120 mm.
3. Which scale would be most suitable for showing the layout of an entire power plant site on an A3 sheet?
Site layouts are large; a small scale like 1:1000 reduces the real size enough to fit on an A3 sheet while keeping the overall arrangement visible.
4. A drawing shows a shaft 75 mm long at scale 2:1. What is the actual (real) length of the shaft?
Scale 2:1 is an enlargement: drawing = 2 × actual. So actual = drawing ÷ 2 = 75 ÷ 2 = 37.5 mm.
5. Which of these is the correct way to write a metric drawing scale for a half-size reduction?
A half-size reduction means one unit on the drawing equals two units on the object, written 1:2. 2:1 would be an enlargement.
6. On a drawing at scale 1:50, a pipe length measures 8 cm. What is the actual length in metres?
1:50 means multiply drawing measure by 50. 8 cm × 50 = 400 cm = 4 m.
7. Why do engineers include a scale bar on a drawing?
A scale bar provides a direct visual reference so that measurements can be checked even when the drawing size changes due to copying or scanning.
8. Which scale is best when you want to show small details larger for clarity (enlargement)?
A scale of 5:1 is an enlargement: drawing is five times larger than the actual object, useful for showing small details clearly.
9. A blueprint title block lists the scale as "Not to scale". What does this mean?
"Not to scale" means the drawing is not created with a consistent scale, so you must use the written dimensions rather than measuring the drawing.
10. If a general arrangement drawing is at 1:200 and a detail view is at 1:2, how do the sizes of the detail compare to the general arrangement?
A detail view at 1:2 is an enlargement compared to 1:200; it shows a small area much larger on the paper for clarity.
11. To convert a drawing length measured in centimetres to real metres using scale 1:25, which process is correct?
Drawing cm × 25 gives real cm, then ÷100 converts cm to metres. For example, 4 cm ×25 =100 cm =1 m.
12. Which scale is equal to full size (actual size) for a component drawing?
A 1:1 scale means one unit on the drawing equals one unit on the actual object — full (true) size.
13. You need to fit a conveyor belt 18 m long onto a drawing sheet. Which of these drawing scales would produce a drawing length closest to 18 cm?
At 1:100, 18 m (1800 cm) ÷100 = 18 cm on paper. 1:10 would give 180 cm which is too large.
14. On an assembly drawing, the notation 1:5 is used for a particular view. What does this tell the student?
1:5 means one unit on drawing equals five units on the object — a reduction (smaller) by a factor of 5.
15. A panel drawing uses scale 1:25. If a bolt head on the drawing measures 6 mm, what is the actual diameter in millimetres?
Multiply drawing size by scale denominator: 6 mm × 25 = 150 mm actual diameter.
16. Which instrument is safest to use for measuring a drawing length on the paper before converting by scale?
A steel rule with mm markings gives accurate linear measurements on paper, required for precise scale conversion.
17. A real pipe length is 3.6 m and is drawn at 3:1. What is the drawing length in centimetres?
3:1 is an enlargement: drawing = 3 × actual. 3.6 m = 360 cm; 360 × 3 = 1080 cm.
18. Which statement is correct about the denominator in a ratio scale 1:n?
In 1:n, the denominator n indicates the real object is n times larger than what is shown on the drawing.
19. If you copy a drawing and the copy is 150% of the original size, how must you adjust measured lengths before using the original scale 1:50?
The copy is enlarged by 1.5 times; to get original drawing measurements, divide by 1.5, then convert using 1:50 to find real sizes.
20. A drawing is annotated with scale 1:25 and units are millimetres. A dimension shows 250. What is the actual measurement and its unit?
Dimension 250 (interpreted as 250 mm on drawing) × 25 = 6250 mm = 6.25 m actual.
21. When preparing a workshop drawing for machining a small gear, which scale is most appropriate to show teeth clearly?
Small features like gear teeth often need enlargement; 2:1 doubles size on paper to show teeth clearly for machining instructions.
22. On an electrical layout for a generator room, which scale notation is most commonly used in Kenya (metric system)?
Kenya uses the metric system; scales like 1:100 are standard for room and building layouts, unlike imperial inch-foot notations.
23. Which error will give a wrong actual size when using a reduced drawing without checking scale?
If the drawing has been photocopied or reduced, the listed scale no longer matches the paper measurement; converting without adjusting will produce incorrect actual sizes.
24. Which method is correct for indicating a different scale for one view on a multi-view drawing sheet?
Each view that departs from the sheet's main scale must be labeled with its own scale next to the view so readers know how to interpret measurements.
25. A student measures 30 mm on a drawing with scale 1:125. What is the actual length in metres?
30 mm × 125 = 3750 mm = 3.75 m actual length.
26. Why might a drawing use different scales for general arrangement and detail drawings?
Different scales let the drafter present both the overall layout (small scale) and close-up details (large scale) so fabrication and inspection can be done accurately.