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Date May 2017 Marks available 3 Reference code 17M.2.AHL.TZ1.H_8
Level Additional Higher Level Paper Paper 2 Time zone Time zone 1
Command term Find Question number H_8 Adapted from N/A

Question

A water trough which is 10 metres long has a uniform cross-section in the shape of a semicircle with radius 0.5 metres. It is partly filled with water as shown in the following diagram of the cross-section. The centre of the circle is O and the angle KOL is θ radians.

M17/5/MATHL/HP2/ENG/TZ1/08

The volume of water is increasing at a constant rate of 0.0008 m3s1.

Find an expression for the volume of water V (m3) in the trough in terms of θ.

[3]
a.

Calculate dθdt when θ=π3.

[4]
b.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

area of segment =12×0.52×(θsinθ)     M1A1

V=area of segment×10

V=54(θsinθ)     A1

[3 marks]

a.

METHOD 1

dVdt=54(1cosθ)dθdt     M1A1

0.0008=54(1cosπ3)dθdt     (M1)

dθdt=0.00128 (rads1)     A1

METHOD 2

dθdt=dθdV×dVdt     (M1)

dVdθ=54(1cosθ)     A1

dθdt=4×0.00085(1cosπ3)     (M1)

dθdt=0.00128(43125)(rad s1)     A1

[4 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 5 —Calculus » SL 5.3—Differentiating polynomials, n E Z
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Topic 3— Geometry and trigonometry » SL 3.4—Circle: radians, arcs, sectors
Topic 5 —Calculus » SL 5.6—Differentiating polynomials n E Q. Chain, product and quotient rules
Topic 5 —Calculus » AHL 5.14—Implicit functions, related rates, optimisation
Topic 3— Geometry and trigonometry
Topic 5 —Calculus

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