Taking readings
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Use these readings to help you answer the questions below. Consider and jot down an answer from one of the multiple choices before you scroll down to find out how you went.
Question 1
Point D is at exactly the same height as the top of the concrete block you are using as your datum point.
True
False
Answer
If you answered:
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True, then you are correct, both measure 1.50 m.
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False, you would be incorrect. Check again and you will see that both points measure 1.50 m.
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Question 2
Point C is at 1.89, point A is at 1.87. Which ground level is lower?
Point C
Point A
Answer
If you answered:
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Point C then you are correct, well done. Point C has the higher measurement so the ground level is lower.
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Point A – sorry but you are incorrect. Remember the rule that the higher the reading, the lower the ground level. Point C has the higher measurement so the ground level is lower.
Question 3
If Point B needs to be excavated by 14 mm what should the staff reading be when the excavation has been correctly completed?
1.89
1.61
1.14
Answer
If you answered:
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1.89 you are correct. Point B is 1.75. If it is lowered by 14 mm its reading is 1.75 + 14mm = 1.89.
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1.61 think again. Point B is 1.75. If it is lowered by 14 mm its reading is 1.75 + 14mm = 1.89.
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1.14 you're way off. Point B is 1.75. If it is lowered by 14 mm its reading is 1.75 + 14mm = 1.89.
Question 4
After the excavation in question three, will Point A need to be raised or lowered to be level with B and C?
Raised by 2 mm – the reading will be 1.85
Raised by 2 mm – the reading will be 1.89
Lowered by 2mm – the reading will be 1.85
Lowered by 2 mm – the reading will be 1.89
Answer
If you answered:
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Raised by 2 mm – the reading will be 1.85, you are incorrect. Point A will need to be lowered, not raised.
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Raised by 2 mm – the reading will be 1.89, you are incorrect. Point A will need to be lowered, not raised.
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Lowered by 2mm – the reading will be 1.85, you are incorrect. Point A will need to be lowered. But remember that the lower a point is the higher the value will be, so the reading should be 2 mm greater than 1.87, not less.
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Lowered by 2 mm – the reading will be 1.89, you are correct. Well done, Point A will need to be lowered, meaning that the staff value will increase to 1.89, the same as Point B and C.
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