Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 287 · 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 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
2. 2.🔺 One side of a straw bridge is a row of 3 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 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?
4. 4.🔺 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) rigid (b) wobbly
5. 5.🔺 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?
6. 6.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) square (c) triangle (d) rectangle
7. 7.🔺 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?
8. 8.True or false: an igloo uses an arch. (a) False (b) True
9. 9.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) paint it (c) take off a side (d) add a diagonal brace
10. 10.🔺 Which strong shape does an electric pylon use? (a) dome (b) beam (c) arch (d) triangle
11. 11.🔺 Which strong shape does a curved stone doorway use? (a) beam (b) arch (c) triangle (d) dome
12. 12.🔺 Which strong shape does a roof truss use? (a) triangle (b) dome (c) arch (d) beam
13. 13.🔺 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
14. 14.True or false: a crane arm uses triangles. (a) False (b) True
15. 15.Which of these uses an arch? (a) a crane arm (b) an electric pylon (c) a fort gateway (d) a plank over a drain
16. 16.True or false: a plank over a drain uses a beam. (a) True (b) False
17. 17.True or false: an igloo uses triangles. (a) False (b) True
18. 18.🔺 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
19. 19.Which of these uses a dome? (a) a bicycle frame (b) a round palace roof (c) a truss bridge side (d) a slab over a canal
20. 20.🔺 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?
21. 21.🔺 Why can an arch carry heavy loads? (a) it is very light (b) it is hollow (c) it bends easily (d) it works in compression
22. 22.True or false: a plank over a drain uses triangles. (a) False (b) True
23. 23.🔺 Which strong shape does a crane arm use? (a) dome (b) beam (c) triangle (d) arch
24. 24.Which of these uses a beam? (a) a slab over a canal (b) an electric pylon (c) a roof truss (d) a planetarium roof
25. 25.🔺 A beam bends under a load. Its top side is … (a) stretched (tension) (b) not affected (c) floating (d) squeezed (compression)
26. 26.🔺 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?
27. 27.True or false: a plank over a drain uses a dome. (a) True (b) False
28. 28.🔺 Which strong shape does a plank over a drain use? (a) beam (b) arch (c) dome (d) triangle
29. 29.🔺 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?
30. 30.🔺 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?
31. 31.🔺 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) rigid (b) wobbly
32. 32.🔺 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?
33. 33.True or false: an old stone bridge uses an arch. (a) False (b) True
34. 34.🔺 One side of a straw bridge is a row of 10 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
35. 35.Which of these uses triangles? (a) a shelf on two brackets (b) a bicycle frame (c) a planetarium roof (d) a slab over a canal
36. 36.True or false: a fort gateway uses an arch. (a) False (b) True
37. 37.True or false: a planetarium roof uses triangles. (a) True (b) False
38. 38.Which of these uses a beam? (a) a truss bridge side (b) an old stone bridge (c) a shelf on two brackets (d) a bicycle frame
39. 39.🔺 Which strong shape does a bicycle frame use? (a) dome (b) triangle (c) beam (d) arch
40. 40.🔺 Which strong shape does a truss bridge side use? (a) arch (b) beam (c) dome (d) triangle

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