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Science

Force, mass and acceleration

Forces and acceleration calculations

You should know the equation that shows the relationship between resultant force, mass and acceleration, and be able to use it.

The equation

resultant force (newton, N) = mass (kg) × acceleration (m/s2)

You can see from this equation that 1N is the force needed to give 1kg an acceleration of 1m/s2.

  • For example, the force needed to accelerate a 10kg mass by 5m/s2 is:
  • 10 x 5 = 50N
  • The same force could accelerate a 1kg mass by 50m/s2 or a 100kg mass by 0.5m/s2.
  • Putting it simply, we can say that it takes more force to accelerate a larger mass.
Question
  • A truck has a mass of 2,000kg.
  • The driving force created by the engine is 3,000 newtons.
  • Calculate the acceleration caused by this force.

toggle answer

Answer
  1. Write down the equation.
    • force = mass × acceleration
  2. Rearrange the equation.
    • acceleration = forcemass
  3. Put in the values.
    • acceleration = 3,000N2,000kg
  4. Work out the answer and write it down.
    • acceleration = 1.5m/s2

Check your understanding of this section by having a go at the activity.

Back to Forces and motion index

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