Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 195 · 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 2 corner-to-corner braces. Is it rigid or wobbly? (a) wobbly (b) rigid
2. 2.🔺 Which strong shape does a lintel over a door use? (a) triangle (b) beam (c) dome (d) arch
3. 3.🔺 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?
4. 4.🔺 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?
5. 5.True or false: an electric pylon uses triangles. (a) False (b) True
6. 6.🔺 Why can an arch carry heavy loads? (a) it bends easily (b) it works in compression (c) it is very light (d) it is hollow
7. 7.True or false: a planetarium roof uses triangles. (a) True (b) False
8. 8.🔺 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?
9. 9.🔺 Which strong shape does a crane arm use? (a) dome (b) arch (c) beam (d) triangle
10. 10.🔺 Which strong shape does an igloo use? (a) dome (b) triangle (c) beam (d) arch
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.🔺 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?
13. 13.🔺 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?
14. 14.🔺 A frame shaped like a pentagon is made of straws joined by loose pins, with 1 corner-to-corner brace. Is it rigid or wobbly? (a) rigid (b) wobbly
15. 15.🔺 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?
16. 16.🔺 Which strong shape does an old stone bridge use? (a) arch (b) dome (c) beam (d) triangle
17. 17.🔺 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?
18. 18.🔺 A beam bends under a load. Its top side is … (a) floating (b) stretched (tension) (c) not affected (d) squeezed (compression)
19. 19.True or false: a curved stone doorway uses triangles. (a) True (b) False
20. 20.🔺 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?
21. 21.True or false: an igloo uses a dome. (a) False (b) True
22. 22.🔺 Which strong shape does a planetarium roof use? (a) beam (b) dome (c) triangle (d) arch
23. 23.🔺 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?
24. 24.True or false: a truss bridge side uses triangles. (a) False (b) True
25. 25.🔺 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?
26. 26.🔺 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?
27. 27.🔺 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
28. 28.🔺 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?
29. 29.True or false: an old stone bridge uses triangles. (a) True (b) False
30. 30.🔺 Which strong shape does a bicycle frame use? (a) arch (b) dome (c) beam (d) triangle
31. 31.🔺 A frame shaped like a hexagon 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.True or false: a round palace roof uses a dome. (a) False (b) True
33. 33.Which of these uses an arch? (a) an igloo (b) a bicycle frame (c) a round palace roof (d) a curved stone doorway
34. 34.Which of these uses a dome? (a) an electric pylon (b) a plank over a drain (c) a planetarium roof (d) a lintel over a door
35. 35.🔺 Which shape keeps its shape best when its corners are pinned? (a) hexagon (b) square (c) triangle (d) rectangle
36. 36.True or false: a bicycle frame uses a dome. (a) False (b) True
37. 37.🔺 One side of a straw bridge is a row of 1 triangle standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
38. 38.🔺 Which strong shape does an electric pylon use? (a) beam (b) arch (c) dome (d) triangle
39. 39.Which of these uses a beam? (a) a shelf on two brackets (b) a roof truss (c) a curved stone doorway (d) a planetarium roof
40. 40.🔺 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?

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