Skip to content

Course home

Sign up

9.9 Using Second Derivatives

EasyMediumHard
12345678910111213
Question 10

The power consumption PPP (in kW) of an industrial extractor fan is modelled by the equation

P=13w3−6w+kw,w>0 P = \frac{1}{3}w^3 - 6w + \frac{k}{w}, \quad w > 0 P=31​w3−6w+wk​,w>0

where www is the angular velocity in rad/s and kkk is a constant. The fan is observed to have a stationary point in its power profile when w=2w = 2w=2.

a.

Show that k=−8k = -8k=−8.

[3]
b.

Determine the nature of the stationary point when w=2w = 2w=2, justifying your answer.

[3]
c.

The power profile has a second stationary point.

Using algebra, find the exact value of the angular velocity www at this second stationary point.

[3]
Markscheme

9.9 Using Second Derivatives Questions

  1. A Level
  2. /Maths
  3. /9.9 Using Second Derivatives

57 exam-style questions on Edexcel A Level Maths 9.9 Using Second Derivatives. Each one has a worked solution and a mark scheme showing where the marks go.

Question bank