Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 621 · 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.Which of these uses triangles? (a) a plank over a drain (b) a round palace roof (c) a lintel over a door (d) an electric pylon
3. 3.🔺 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) wobbly (b) rigid
4. 4.True or false: an electric pylon uses an arch. (a) True (b) False
5. 5.🔺 Which shape keeps its shape best when its corners are pinned? (a) triangle (b) square (c) hexagon (d) rectangle
6. 6.Which of these uses triangles? (a) a fort gateway (b) a crane arm (c) a shelf on two brackets (d) an old stone bridge
7. 7.Which of these uses triangles? (a) an old stone bridge (b) a round palace roof (c) a curved stone doorway (d) a bicycle frame
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.🔺 Which strong shape does a bicycle frame use? (a) arch (b) beam (c) triangle (d) dome
10. 10.🔺 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?
11. 11.Which of these uses an arch? (a) a plank over a drain (b) a roof truss (c) a shelf on two brackets (d) an old stone bridge
12. 12.🔺 Which strong shape does a crane arm use? (a) beam (b) dome (c) triangle (d) arch
13. 13.🔺 Which strong shape does an igloo use? (a) beam (b) dome (c) triangle (d) arch
14. 14.🔺 Which strong shape does a truss bridge side use? (a) triangle (b) beam (c) arch (d) dome
15. 15.True or false: an electric pylon uses a beam. (a) True (b) False
16. 16.🔺 Which strong shape does a shelf on two brackets use? (a) dome (b) arch (c) beam (d) triangle
17. 17.🔺 Why can an arch carry heavy loads? (a) it is hollow (b) it works in compression (c) it bends easily (d) it is very light
18. 18.True or false: a lintel over a door uses a beam. (a) False (b) True
19. 19.🔺 Which strong shape does a curved stone doorway use? (a) beam (b) dome (c) arch (d) triangle
20. 20.🔺 A beam bends under a load. Its top side is … (a) not affected (b) stretched (tension) (c) squeezed (compression) (d) floating
21. 21.True or false: a curved stone doorway uses a dome. (a) False (b) True
22. 22.True or false: a shelf on two brackets uses a beam. (a) True (b) False
23. 23.Which of these uses triangles? (a) a curved stone doorway (b) a truss bridge side (c) an igloo (d) a plank over a drain
24. 24.Which of these uses a dome? (a) an electric pylon (b) an igloo (c) a crane arm (d) a roof truss
25. 25.🔺 One side of a straw bridge is a row of 15 triangles standing point-up and point-down in turn, each sharing a side with the next. How many straws does it use?
26. 26.🔺 How do engineers stop a square frame from wobbling? (a) paint it (b) take off a side (c) make it bigger (d) add a diagonal brace
27. 27.True or false: a crane arm uses an arch. (a) True (b) False
28. 28.🔺 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?
29. 29.🔺 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?
30. 30.🔺 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
31. 31.🔺 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?
32. 32.🔺 Which strong shape does a roof truss use? (a) dome (b) beam (c) triangle (d) arch
33. 33.True or false: a truss bridge side uses a beam. (a) True (b) False
34. 34.🔺 Which strong shape does an electric pylon use? (a) beam (b) triangle (c) arch (d) dome
35. 35.🔺 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?
36. 36.True or false: a roof truss uses triangles. (a) True (b) False
37. 37.🔺 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?
38. 38.🔺 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?
39. 39.True or false: an old stone bridge uses a beam. (a) True (b) False
40. 40.🔺 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?

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