Mathematics · Pearson Edexcel 9MA0 · Topic 8

Forces and Newton's laws

Forces and Newton's laws: resolving forces, inclined planes, connected particles, pulleys and friction.

  • 6 sub-topics
  • 2 in Year 12, 2 in Year 13
  • 78 practice questions
  • 6 animated lessons
Practice questions (78) Lessons Worksheets All Edexcel Mathematics topics

What the specification says

Every sub-topic Pearson Edexcel can examine in this topic, with its reference number from the official specification. The Y12 and Y13 tags show when each sub-topic is usually taught.

  1. 8.1Forces and Newton's first lawY12
  2. 8.2Newton's second law and resolving forcesY13
  3. 8.3Weight and motion under gravityY12
  4. 8.4Newton's third law, equilibrium and connected particlesY13
  5. 8.5Resultant forces and dynamics in a planeY13
  6. 8.6Friction, F ≤ μRY13

Try 3 questions

Easy, medium and hard questions from this topic, each with a worked solutions and the mark for every step. All 78 questions in this topic, free, no account needed.

Forces and Newton's laws

Easy

Newton's second law · Year 12 · 2 marks

  1. A car of mass 1000 kg has a driving force of 2500 N and resistance of 700 N. Find its acceleration.
    (2)
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  1. Resultant force = mass × acceleration.2500−700=1000a2500 - 700 = 1000a
  2. a=1.8a = 1.8 m s⁻²

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Forces and Newton's laws

Medium

Particle on an inclined plane · Year 12 · 4 marks

A particle of mass 2 kg is pulled up a smooth plane inclined at 30° to the horizontal by a force of 15 N acting parallel to the plane. Take g=9.8 m s−2g = 9.8\ \mathrm{m\,s^{-2}}.
  1. Find the acceleration of the particle.
    (4)
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  1. Resolve along the plane and use F=maF = ma. The weight's component down the slope is mgsin⁡30∘mg\sin 30^\circ.15−2gsin⁡30∘=2a15 - 2g\sin 30^\circ = 2a
  2. 2×9.8×0.5=9.82 \times 9.8 \times 0.5 = 9.8.15−9.8=2a15 - 9.8 = 2a
  3. The plane is smooth, so there is no friction to include.a=2.6 m s−2a = 2.6\ \mathrm{m\,s^{-2}} up the plane

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Forces and Newton's laws

Not needed for Year 12Hard

Pushing up a rough slope · Year 13 · 6 marks

  1. A 10 kg box is on a rough plane inclined at 20∘20^\circ (μ=0.4\mu = 0.4). Find the force parallel to the plane needed to make the box just about to move up.
    (6)
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  1. R=10gcos⁡20∘=92.1R = 10g\cos 20^\circ = 92.1 N
  2. Friction opposes the movement that is about to happen.Friction acts down the slope: F=0.4RF = 0.4R
  3. Forces up the slope balance forces down it.PP=10gsin⁡20∘{}= 10g\sin 20^\circ+0.4×10gcos⁡20∘{}+ 0.4 \times 10g\cos 20^\circ
  4. P=70.4P = 70.4 N

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