Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 675 · 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.🔺 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?
2. 2.🔺 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
3. 3.🔺 Which strong shape does a planetarium roof use? (a) dome (b) triangle (c) beam (d) arch
4. 4.🔺 Which strong shape does a lintel over a door use? (a) dome (b) beam (c) triangle (d) arch
5. 5.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) square (c) triangle (d) hexagon
6. 6.True or false: an electric pylon uses an arch. (a) False (b) True
7. 7.🔺 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?
8. 8.🔺 How do engineers stop a square frame from wobbling? (a) take off a side (b) add a diagonal brace (c) paint it (d) make it bigger
9. 9.🔺 Which strong shape does an electric pylon use? (a) beam (b) dome (c) triangle (d) arch
10. 10.🔺 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?
11. 11.🔺 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
12. 12.🔺 Which strong shape does a truss bridge side use? (a) triangle (b) beam (c) dome (d) arch
13. 13.True or false: a plank over a drain uses triangles. (a) False (b) True
14. 14.Which of these uses triangles? (a) a truss bridge side (b) a planetarium roof (c) a shelf on two brackets (d) a lintel over a door
15. 15.🔺 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?
16. 16.Which of these uses an arch? (a) a truss bridge side (b) an igloo (c) a round palace roof (d) a fort gateway
17. 17.Which of these uses triangles? (a) a lintel over a door (b) a shelf on two brackets (c) an old stone bridge (d) a bicycle frame
18. 18.🔺 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
19. 19.True or false: a roof truss uses an arch. (a) True (b) False
20. 20.True or false: a fort gateway uses an arch. (a) True (b) False
21. 21.🔺 Which strong shape does a plank over a drain use? (a) beam (b) dome (c) triangle (d) arch
22. 22.🔺 Which strong shape does a bicycle frame use? (a) dome (b) beam (c) arch (d) triangle
23. 23.🔺 Which strong shape does a fort gateway use? (a) triangle (b) dome (c) beam (d) arch
24. 24.Which of these uses an arch? (a) an electric pylon (b) a lintel over a door (c) a planetarium roof (d) a curved stone doorway
25. 25.🔺 Which strong shape does a shelf on two brackets use? (a) arch (b) dome (c) beam (d) triangle
26. 26.True or false: a truss bridge side uses an arch. (a) False (b) True
27. 27.Which of these uses a beam? (a) an old stone bridge (b) a crane arm (c) a curved stone doorway (d) a shelf on two brackets
28. 28.🔺 A frame shaped like a pentagon is made of straws joined by loose pins, with 0 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
29. 29.🔺 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?
30. 30.🔺 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?
31. 31.True or false: an electric pylon uses a beam. (a) True (b) False
32. 32.Which of these uses an arch? (a) an old stone bridge (b) a slab over a canal (c) a round palace roof (d) an igloo
33. 33.🔺 A frame shaped like a hexagon is made of straws joined by loose pins, with 3 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
34. 34.Which of these uses a dome? (a) a shelf on two brackets (b) a planetarium roof (c) a roof truss (d) an electric pylon
35. 35.🔺 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?
36. 36.🔺 One side of a straw bridge is a row of 15 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
37. 37.🔺 Which strong shape does an old stone bridge use? (a) triangle (b) arch (c) dome (d) beam
38. 38.🔺 Which strong shape does a slab over a canal use? (a) dome (b) arch (c) triangle (d) beam
39. 39.🔺 A flat frame has 8 straight sides joined by loose pins at the corners. What is the least number of corner-to-corner braces needed to make it rigid?
40. 40.🔺 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?

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