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4.9 Forces and Newton's laws (A-level only)

4.9 Forces and Newton's laws (A-level only)

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Question 30

Use g=9.8g = 9.8g=9.8 m s−2^{-2}−2.

A block of mass 4 kg rests on a rough horizontal plane. The coefficient of friction between the block and the plane is 0.5.

A force of magnitude P P\,P newtons is applied to the block at an angle θ \theta\,θ above the horizontal, and the block is on the point of moving.

a.

Show that P=2gcos⁡θ+0.5sin⁡θ\displaystyle P = \frac{2g}{\cos\theta + 0.5\sin\theta}P=cosθ+0.5sinθ2g​.

[3]
b.

Find the value of θ \theta\,θ for which P P\,P takes its least value, and find that least value of PPP.

[4]
Markscheme

4.9 Forces and Newton's laws (A-level only) Questions

  1. A Level
  2. /Maths
  3. /4.9 Forces and Newton's laws (A-level only)

106 exam-style questions on WJEC A Level Maths 4.9 Forces and Newton's laws (A-level only), covering 4.9.1 Forces and Newton's laws (A-level only), 4.9.2 Forces and Newton's laws (A-level only), 4.9.3 Forces and Newton's laws (A-level only), 4.9.4 Forces and Newton's laws (A-level only), and 4.9.5 Forces and Newton's laws (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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