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AlgebraEasy–MediumMeaning of the constant in a pressure model

Algebra practice question

The pressure p, in kilopascals, at a depth of d metres in a lake is modelled by p = 100 + 9.8d. What does the number 100 represent in this model?

  1. A. The pressure at the surface of the lakeCorrect
  2. B. The increase in pressure for each metre of depth
  3. C. The depth at which the pressure is zero
  4. D. The maximum pressure in the lake

Answer: A. The pressure at the surface of the lake

At d = 0 the pressure is 100.

Why the other answers are wrong

B. The increase in pressure for each metre of depth
The increase per metre is 9.8.
C. The depth at which the pressure is zero
The pressure is never zero in this model.
D. The maximum pressure in the lake
Pressure keeps increasing with depth.

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