DP Physics (last assessment 2024)

Question 19N.3.HL.TZ0.9b

Date	November 2019	Marks available	[Maximum mark: 3]	Reference code	19N.3.HL.TZ0.9b
Level	HL	Paper	3	Time zone	TZ0
Command term	Determine	Question number	b	Adapted from	N/A

[Maximum mark: 3]

19N.3.HL.TZ0.9b

A Pitot tube shown in the diagram is used to determine the speed of air flowing steadily in a horizontal wind tunnel. The narrow tube between points A and B is filled with a liquid. At point B the speed of the air is zero.

(b)

The density of the liquid in the tube is 8.7 × 10²kg m^–3 and the density of air is 1.2 kg m^–3. The difference in the level of the liquid is 6.0 cm. Determine the speed of air at A.

[3]

Markscheme

« $ρ_{liquid} g h = 0.5 \times ρ_{air} v^{2}$ »

difference in pressure $P_{B} - P_{A} = 8.7 \times 10^{2} \times 9.8 \times 0.06 = 510$ «Pa» ✔

correct substitution into the Bernoulli equation, eg: $\frac{1}{2} \times 1.2 v^{2} = 510$ ✔

$v = 29$ «ms^–1» ✔

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Option B: Engineering physics

Option B: Engineering physics » Option B: Engineering physics (Additional higher level option topics) » B.3 – Fluids and fluid dynamics (HL only)

Option B: Engineering physics » Option B: Engineering physics (Additional higher level option topics)

Question 19N.3.HL.TZ0.9b

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