Engineering Worksheet: Strong Shapes

Engineering lesson 17: Strong shapes: triangles, arches and beams · Set 628 · 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 1 corner-to-corner brace. Is it rigid or wobbly? (a) rigid (b) wobbly
2. 2.🔺 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?
3. 3.🔺 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
4. 4.🔺 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?
5. 5.🔺 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?
6. 6.Which of these uses a beam? (a) a roof truss (b) a curved stone doorway (c) a shelf on two brackets (d) a crane arm
7. 7.🔺 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?
8. 8.🔺 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
9. 9.🔺 How do engineers stop a square frame from wobbling? (a) make it bigger (b) take off a side (c) add a diagonal brace (d) paint it
10. 10.True or false: a round palace roof uses a dome. (a) True (b) False
11. 11.Which of these uses a dome? (a) an electric pylon (b) a plank over a drain (c) a planetarium roof (d) a fort gateway
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.True or false: a planetarium roof uses triangles. (a) True (b) False
14. 14.🔺 Why can an arch carry heavy loads? (a) it is very light (b) it is hollow (c) it bends easily (d) it works in compression
15. 15.🔺 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?
16. 16.🔺 Which strong shape does a slab over a canal use? (a) arch (b) triangle (c) beam (d) dome
17. 17.🔺 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?
18. 18.🔺 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
19. 19.🔺 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?
20. 20.True or false: an electric pylon uses triangles. (a) False (b) True
21. 21.True or false: a roof truss uses a dome. (a) True (b) False
22. 22.🔺 Which shape keeps its shape best when its corners are pinned? (a) rectangle (b) hexagon (c) square (d) triangle
23. 23.🔺 Which strong shape does a truss bridge side use? (a) arch (b) dome (c) triangle (d) beam
24. 24.🔺 Which strong shape does a plank over a drain use? (a) dome (b) triangle (c) beam (d) arch
25. 25.🔺 Which strong shape does an igloo use? (a) dome (b) arch (c) triangle (d) beam
26. 26.🔺 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
27. 27.🔺 Which strong shape does a fort gateway use? (a) arch (b) triangle (c) beam (d) dome
28. 28.Which of these uses a dome? (a) a plank over a drain (b) a round palace roof (c) a shelf on two brackets (d) a bicycle frame
29. 29.🔺 Which strong shape does a planetarium roof use? (a) triangle (b) arch (c) beam (d) dome
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) rigid (b) wobbly
31. 31.Which of these uses a dome? (a) an electric pylon (b) an igloo (c) a crane arm (d) a truss bridge side
32. 32.True or false: a lintel over a door uses a beam. (a) True (b) False
33. 33.True or false: a planetarium roof uses a dome. (a) False (b) True
34. 34.🔺 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) rigid (b) wobbly
35. 35.🔺 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?
36. 36.Which of these uses a beam? (a) a bicycle frame (b) a plank over a drain (c) an old stone bridge (d) a crane arm
37. 37.Which of these uses an arch? (a) a curved stone doorway (b) a round palace roof (c) a truss bridge side (d) a planetarium roof
38. 38.True or false: a truss bridge side uses an arch. (a) False (b) True
39. 39.🔺 A beam bends under a load. Its top side is … (a) squeezed (compression) (b) stretched (tension) (c) not affected (d) floating
40. 40.🔺 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?

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