Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 604 · 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 11 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
2. 2.🔺 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?
3. 3.Which of these uses a dome? (a) an electric pylon (b) a bicycle frame (c) a planetarium roof (d) an old stone bridge
4. 4.True or false: a plank over a drain uses a beam. (a) True (b) False
5. 5.Which of these uses triangles? (a) a lintel over a door (b) a fort gateway (c) a round palace roof (d) a roof truss
6. 6.Which of these uses an arch? (a) a shelf on two brackets (b) a round palace roof (c) an old stone bridge (d) an electric pylon
7. 7.🔺 A frame shaped like a square is made of straws joined by loose pins, with 1 corner-to-corner brace. Is it rigid or wobbly? (a) wobbly (b) rigid
8. 8.🔺 A frame shaped like a square is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
9. 9.🔺 Which strong shape does an old stone bridge use? (a) arch (b) triangle (c) dome (d) beam
10. 10.🔺 Which strong shape does a lintel over a door use? (a) arch (b) triangle (c) dome (d) beam
11. 11.🔺 A flat frame has 10 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
12. 12.🔺 A flat frame has 4 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
13. 13.True or false: a bicycle frame uses triangles. (a) True (b) False
14. 14.🔺 Which strong shape does a crane arm use? (a) triangle (b) dome (c) beam (d) arch
15. 15.🔺 One side of a straw bridge is a row of 5 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
16. 16.Which of these uses triangles? (a) a crane arm (b) a shelf on two brackets (c) a fort gateway (d) a plank over a drain
17. 17.🔺 One side of a straw bridge is a row of 7 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
18. 18.🔺 Which strong shape does a shelf on two brackets use? (a) beam (b) dome (c) arch (d) triangle
19. 19.🔺 Which strong shape does a fort gateway use? (a) dome (b) beam (c) arch (d) triangle
20. 20.🔺 A frame shaped like a triangle is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) rigid (b) wobbly
21. 21.🔺 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?
22. 22.🔺 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?
23. 23.True or false: a slab over a canal uses a beam. (a) False (b) True
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) wobbly (b) rigid
25. 25.True or false: a lintel over a door uses a beam. (a) False (b) True
26. 26.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) take off a side (c) paint it (d) add a diagonal brace
27. 27.🔺 Which shape keeps its shape best when its corners are pinned? (a) square (b) triangle (c) rectangle (d) hexagon
28. 28.🔺 A flat frame has 11 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
29. 29.True or false: a curved stone doorway uses an arch. (a) False (b) True
30. 30.Which of these uses a dome? (a) an igloo (b) a slab over a canal (c) a lintel over a door (d) a shelf on two brackets
31. 31.True or false: a truss bridge side uses a dome. (a) False (b) True
32. 32.True or false: a planetarium roof uses a dome. (a) False (b) True
33. 33.🔺 One side of a straw bridge is a row of 14 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
34. 34.Which of these uses an arch? (a) a crane arm (b) a slab over a canal (c) an igloo (d) a fort gateway
35. 35.🔺 A flat frame has 12 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
36. 36.True or false: an electric pylon uses triangles. (a) True (b) False
37. 37.🔺 Which strong shape does a roof truss use? (a) dome (b) beam (c) arch (d) triangle
38. 38.🔺 Which strong shape does a planetarium roof use? (a) arch (b) triangle (c) beam (d) dome
39. 39.🔺 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?
40. 40.Which of these uses triangles? (a) a planetarium roof (b) a truss bridge side (c) a plank over a drain (d) a lintel over a door

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