Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 203 · 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 5 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 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?
3. 3.🔺 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
4. 4.🔺 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?
5. 5.🔺 Which strong shape does a crane arm use? (a) beam (b) arch (c) dome (d) triangle
6. 6.🔺 Which shape keeps its shape best when its corners are pinned? (a) triangle (b) square (c) hexagon (d) rectangle
7. 7.Which of these uses a dome? (a) a crane arm (b) a slab over a canal (c) a truss bridge side (d) a planetarium roof
8. 8.🔺 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?
9. 9.🔺 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?
10. 10.🔺 Which strong shape does a roof truss use? (a) beam (b) arch (c) triangle (d) dome
11. 11.🔺 Which strong shape does a curved stone doorway use? (a) arch (b) beam (c) triangle (d) dome
12. 12.True or false: a bicycle frame uses an arch. (a) True (b) False
13. 13.🔺 Which strong shape does a slab over a canal use? (a) beam (b) dome (c) triangle (d) arch
14. 14.Which of these uses triangles? (a) a fort gateway (b) a lintel over a door (c) an electric pylon (d) a round palace roof
15. 15.🔺 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) wobbly (b) rigid
16. 16.Which of these uses a dome? (a) a plank over a drain (b) an igloo (c) an electric pylon (d) a shelf on two brackets
17. 17.🔺 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?
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 triangles? (a) a round palace roof (b) a roof truss (c) a plank over a drain (d) an old stone bridge
20. 20.Which of these uses triangles? (a) a round palace roof (b) a fort gateway (c) a curved stone doorway (d) a crane arm
21. 21.🔺 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
22. 22.🔺 Which strong shape does a round palace roof use? (a) arch (b) beam (c) dome (d) triangle
23. 23.🔺 Which strong shape does an electric pylon use? (a) triangle (b) dome (c) beam (d) arch
24. 24.🔺 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
25. 25.🔺 Which strong shape does a planetarium roof use? (a) beam (b) triangle (c) dome (d) arch
26. 26.Which of these uses a beam? (a) a lintel over a door (b) a round palace roof (c) an electric pylon (d) a truss bridge side
27. 27.🔺 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
28. 28.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it bends easily (c) it works in compression (d) it is very light
29. 29.True or false: a fort gateway uses an arch. (a) True (b) False
30. 30.Which of these uses a dome? (a) a shelf on two brackets (b) a slab over a canal (c) a roof truss (d) a round palace roof
31. 31.True or false: a bicycle frame uses triangles. (a) True (b) False
32. 32.True or false: an igloo uses a dome. (a) False (b) True
33. 33.True or false: an electric pylon uses triangles. (a) False (b) True
34. 34.🔺 Which strong shape does a fort gateway use? (a) arch (b) dome (c) triangle (d) beam
35. 35.True or false: a crane arm uses triangles. (a) False (b) True
36. 36.🔺 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?
37. 37.🔺 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
38. 38.True or false: a bicycle frame uses a beam. (a) False (b) True
39. 39.Which of these uses a beam? (a) an electric pylon (b) a slab over a canal (c) a roof truss (d) a curved stone doorway
40. 40.🔺 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?

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