Pressure and depth
4 marks · NormalThe table gives data about liquid Y at different depths.
| Depth / m | Pressure difference / Pa |
|---|---|
| 1.0 | 8500 |
| 2.0 | 17000 |
| 3.0 | 25500 |
Calculate the density of liquid Y. Take g = 8.5 N/kg.
Describe the relationship between depth and pressure difference in liquid Y.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) 1000 kg/m³ · must show use any table row data correctly, correct calculation of density
(b) Pressure difference increases linearly with depth · must show mentions linear/proportional
Common mistakes: Using the wrong row of data or the wrong g
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Rearranges p = hρg for density
M2 (a) · 1 mark · Correct substitution (e.g. 8500/(1.0 × 8.5))
A1 (a) · 1 mark · Evaluates correct density (1000 kg/m^3) from any correct row (follow-through)
B1 (b) · 1 mark · States correct relationship (linear or proportional)
Worked solution
a) Use . Using row 1:
b) Pressure difference is directly proportional to depth (each 1 m increase gives 8500 Pa more).