Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 646 · 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 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?
2. 2.🔺 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?
3. 3.🔺 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?
4. 4.True or false: an electric pylon uses an arch. (a) True (b) False
5. 5.Which of these uses a dome? (a) a plank over a drain (b) a slab over a canal (c) a shelf on two brackets (d) a planetarium roof
6. 6.🔺 Which strong shape does an old stone bridge use? (a) beam (b) triangle (c) dome (d) arch
7. 7.🔺 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?
8. 8.🔺 Which strong shape does an electric pylon use? (a) beam (b) triangle (c) arch (d) dome
9. 9.🔺 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?
10. 10.🔺 Which strong shape does a crane arm use? (a) dome (b) beam (c) arch (d) triangle
11. 11.True or false: a slab over a canal uses a beam. (a) True (b) False
12. 12.🔺 Which strong shape does a roof truss use? (a) dome (b) arch (c) triangle (d) beam
13. 13.True or false: a fort gateway uses an arch. (a) False (b) True
14. 14.🔺 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
15. 15.Which of these uses a dome? (a) a crane arm (b) an igloo (c) a curved stone doorway (d) an old stone bridge
16. 16.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) triangle (c) square (d) hexagon
17. 17.Which of these uses triangles? (a) an old stone bridge (b) an igloo (c) a fort gateway (d) an electric pylon
18. 18.🔺 Which strong shape does a curved stone doorway use? (a) beam (b) triangle (c) arch (d) dome
19. 19.🔺 Which strong shape does a round palace roof use? (a) triangle (b) beam (c) arch (d) dome
20. 20.🔺 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
21. 21.🔺 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?
22. 22.🔺 A beam bends under a load. Its top side is … (a) not affected (b) floating (c) squeezed (compression) (d) stretched (tension)
23. 23.Which of these uses an arch? (a) a crane arm (b) an electric pylon (c) a fort gateway (d) a lintel over a door
24. 24.Which of these uses an arch? (a) a bicycle frame (b) an electric pylon (c) a slab over a canal (d) an old stone bridge
25. 25.🔺 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?
26. 26.🔺 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?
27. 27.🔺 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
28. 28.🔺 Which strong shape does a planetarium roof use? (a) beam (b) triangle (c) arch (d) dome
29. 29.🔺 Which strong shape does a truss bridge side use? (a) arch (b) dome (c) beam (d) triangle
30. 30.Which of these uses an arch? (a) a truss bridge side (b) an electric pylon (c) a curved stone doorway (d) a bicycle frame
31. 31.🔺 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?
32. 32.Which of these uses triangles? (a) an igloo (b) a plank over a drain (c) a planetarium roof (d) a crane arm
33. 33.🔺 Which strong shape does a shelf on two brackets use? (a) triangle (b) arch (c) dome (d) beam
34. 34.True or false: a curved stone doorway uses a beam. (a) False (b) True
35. 35.🔺 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?
36. 36.True or false: a fort gateway uses a dome. (a) True (b) False
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.🔺 Why can an arch carry heavy loads? (a) it is very light (b) it is hollow (c) it works in compression (d) it bends easily
39. 39.True or false: a crane arm uses triangles. (a) True (b) False
40. 40.True or false: a lintel over a door uses a beam. (a) False (b) True

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