Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 392 · 40 questions

Engineer's tip (Triangles stay put): Triangles are rigid; trusses, towers and frames use them. A pin-jointed frame with n sides needs n − 3 corner-to-corner braces; a row of n triangles uses 2n + 1 straws. Arches squeeze (compression); beams span gaps; domes are arches turned round in a circle.

1. 1.🔺 One side of a straw bridge is a row of 12 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
2. 2.🔺 One side of a straw bridge is a row of 2 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
3. 3.🔺 A flat frame has 7 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
4. 4.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) rectangle (c) triangle (d) square
5. 5.🔺 A flat frame has 9 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
6. 6.🔺 A flat frame has 5 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
7. 7.True or false: an old stone bridge uses triangles. (a) True (b) False
8. 8.True or false: a roof truss uses triangles. (a) False (b) True
9. 9.Which of these uses triangles? (a) a curved stone doorway (b) a slab over a canal (c) a truss bridge side (d) a fort gateway
10. 10.🔺 Which strong shape does a crane arm use? (a) dome (b) beam (c) triangle (d) arch
11. 11.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) add a diagonal brace (c) take off a side (d) make it bigger
12. 12.🔺 Which strong shape does a round palace roof use? (a) arch (b) beam (c) dome (d) triangle
13. 13.🔺 Which strong shape does a lintel over a door use? (a) triangle (b) dome (c) arch (d) beam
14. 14.True or false: a crane arm uses triangles. (a) False (b) True
15. 15.Which of these uses an arch? (a) a shelf on two brackets (b) a fort gateway (c) a bicycle frame (d) a roof truss
16. 16.True or false: an old stone bridge uses an arch. (a) False (b) True
17. 17.🔺 A beam bends under a load. Its top side is … (a) not affected (b) floating (c) squeezed (compression) (d) stretched (tension)
18. 18.Which of these uses triangles? (a) a round palace roof (b) a roof truss (c) a fort gateway (d) an old stone bridge
19. 19.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 1 corner-to-corner brace. Is it rigid or wobbly? (a) wobbly (b) rigid
20. 20.🔺 Which strong shape does an electric pylon use? (a) dome (b) arch (c) triangle (d) beam
21. 21.🔺 A flat frame has 6 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
22. 22.True or false: a crane arm uses a beam. (a) True (b) False
23. 23.🔺 One side of a straw bridge is a row of 8 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
24. 24.🔺 A frame shaped like a pentagon is made of straws joined by loose pins, with 2 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
25. 25.Which of these uses a dome? (a) a crane arm (b) a lintel over a door (c) a bicycle frame (d) a round palace roof
26. 26.Which of these uses an arch? (a) a lintel over a door (b) a curved stone doorway (c) a round palace roof (d) a shelf on two brackets
27. 27.True or false: a plank over a drain uses triangles. (a) True (b) False
28. 28.Which of these uses triangles? (a) a curved stone doorway (b) a planetarium roof (c) a shelf on two brackets (d) a bicycle frame
29. 29.True or false: a lintel over a door uses a beam. (a) True (b) False
30. 30.True or false: a curved stone doorway uses an arch. (a) False (b) True
31. 31.Which of these uses an arch? (a) a crane arm (b) a planetarium roof (c) a shelf on two brackets (d) an old stone bridge
32. 32.🔺 One side of a straw bridge is a row of 4 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
33. 33.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
34. 34.🔺 Which strong shape does a fort gateway use? (a) arch (b) beam (c) triangle (d) dome
35. 35.🔺 One side of a straw bridge is a row of 9 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
36. 36.🔺 Which strong shape does a bicycle frame use? (a) beam (b) dome (c) triangle (d) arch
37. 37.🔺 One side of a straw bridge is a row of 6 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
38. 38.Which of these uses a beam? (a) a lintel over a door (b) a bicycle frame (c) an igloo (d) a roof truss
39. 39.🔺 Which strong shape does a slab over a canal use? (a) triangle (b) dome (c) beam (d) arch
40. 40.True or false: a roof truss uses a dome. (a) False (b) True

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