Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 298 · 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 pentagon 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.🔺 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
3. 3.🔺 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?
4. 4.🔺 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?
5. 5.True or false: an electric pylon uses an arch. (a) False (b) True
6. 6.Which of these uses an arch? (a) an igloo (b) a slab over a canal (c) a roof truss (d) an old stone bridge
7. 7.🔺 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
8. 8.🔺 Which strong shape does a roof truss use? (a) triangle (b) dome (c) beam (d) arch
9. 9.🔺 How do engineers stop a square frame from wobbling? (a) add a diagonal brace (b) make it bigger (c) paint it (d) take off a side
10. 10.🔺 Why can an arch carry heavy loads? (a) it bends easily (b) it is very light (c) it works in compression (d) it is hollow
11. 11.🔺 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?
12. 12.🔺 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?
13. 13.🔺 Which strong shape does a round palace roof use? (a) arch (b) triangle (c) dome (d) beam
14. 14.🔺 Which strong shape does a lintel over a door use? (a) triangle (b) dome (c) arch (d) beam
15. 15.🔺 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?
16. 16.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) triangle (c) rectangle (d) square
17. 17.🔺 Which strong shape does an igloo use? (a) triangle (b) beam (c) dome (d) arch
18. 18.🔺 Which strong shape does a truss bridge side use? (a) beam (b) arch (c) triangle (d) dome
19. 19.True or false: a plank over a drain uses a beam. (a) True (b) False
20. 20.True or false: a crane arm uses triangles. (a) False (b) True
21. 21.🔺 Which strong shape does an old stone bridge use? (a) arch (b) beam (c) triangle (d) dome
22. 22.🔺 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) wobbly (b) rigid
23. 23.Which of these uses an arch? (a) a truss bridge side (b) a lintel over a door (c) a curved stone doorway (d) a plank over a drain
24. 24.Which of these uses a dome? (a) a lintel over a door (b) a fort gateway (c) a round palace roof (d) a plank over a drain
25. 25.True or false: an igloo uses a dome. (a) True (b) False
26. 26.Which of these uses triangles? (a) a truss bridge side (b) an igloo (c) an old stone bridge (d) a fort gateway
27. 27.🔺 Which strong shape does an electric pylon use? (a) arch (b) triangle (c) dome (d) beam
28. 28.True or false: a shelf on two brackets uses a beam. (a) False (b) True
29. 29.Which of these uses a dome? (a) a fort gateway (b) an old stone bridge (c) an igloo (d) a plank over a drain
30. 30.🔺 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?
31. 31.🔺 Which strong shape does a curved stone doorway use? (a) beam (b) dome (c) arch (d) triangle
32. 32.🔺 Which strong shape does a crane arm use? (a) dome (b) triangle (c) beam (d) arch
33. 33.🔺 Which strong shape does a bicycle frame use? (a) arch (b) beam (c) triangle (d) dome
34. 34.🔺 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?
35. 35.Which of these uses a beam? (a) a plank over a drain (b) a fort gateway (c) a crane arm (d) a bicycle frame
36. 36.Which of these uses a dome? (a) a shelf on two brackets (b) a planetarium roof (c) a curved stone doorway (d) a fort gateway
37. 37.🔺 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?
38. 38.True or false: an electric pylon uses triangles. (a) False (b) True
39. 39.🔺 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?
40. 40.Which of these uses triangles? (a) a fort gateway (b) a slab over a canal (c) a plank over a drain (d) a roof truss

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