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3.3 R: Forces and Newton's laws

3.3 R: Forces and Newton's laws

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Question 23

In this question 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

3.3 R: Forces and Newton's laws Questions

  1. A Level
  2. /Maths
  3. /3.3 R: Forces and Newton's laws

139 exam-style questions on AQA A Level Maths 3.3 R: Forces and Newton's laws, covering 3.3.1 Concept of a force and Newton's first law, 3.3.2 Newton's second law, 3.3.3 Weight and motion under gravity, 3.3.4 Newton's third law and equilibrium, 3.3.5 Addition of forces and resultants (A-level only), and 3.3.6 Friction (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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