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1 Forces and motion

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  1. Forces and motion units

    1. 1.1Core mechanics units

      Use the units kilogram (kg), metre (m), metre per second (m/s), metre per second squared (m/s²), newton (N), second (s) and newton per kilogram (N/kg).

    2. 1.2PAdditional mechanics units

      Use the following units: newton metre (Nm), kilogram metre/second (kg m/s)

  2. (b) Movement and position

    1. Plot and explain distance-time graphs

    2. Know and use average speed = distance moved ÷ time taken.

    3. Practical: investigate the motion of everyday objects such as toy cars or tennis balls

    4. Know and use acceleration = change in velocity ÷ time taken, a = (v − u) ÷ t.

    5. Plot and explain velocity-time graphs

    6. Determine acceleration from the gradient of a velocity-time graph

    7. Determine the distance travelled from the area between a velocity-time graph and the time axis

    8. Use (final speed)² = (initial speed)² + 2 × acceleration × distance moved, v² = u² + 2as.

  3. (c) Forces, movement, shape and momentum

    1. Describe the effects of forces between bodies such as changes in speed, shape or direction

    2. Identify different types of force such as gravitational or electrostatic

    3. Understand how vector quantities differ from scalar quantities

    4. Understand that force is a vector quantity

    5. Calculate the resultant force of forces that act along a line

    6. Know that friction is a force that opposes motion

    7. Know and use unbalanced force = mass × acceleration, F = ma.

    8. Know and use weight = mass × gravitational field strength, W = mg.

    9. Know that the stopping distance of a vehicle is made up of the sum of the thinking distance and the braking distance

    10. Describe the factors affecting vehicle stopping distance, including speed, mass, road condition and reaction time

    11. Describe the forces acting on falling objects (and explain why falling objects reach a terminal velocity)

    12. Practical: investigate how extension varies with applied force for helical springs, metal wires and rubber bands

    13. Know that the initial linear region of a force-extension graph is associated with Hooke’s law

    14. Describe elastic behaviour as the ability of a material to recover its original shape after the forces causing deformation have been removed

    15. Know and use momentum = mass × velocity, p = mv.

    16. Use the idea of momentum to explain safety features

    17. Use the conservation of momentum to calculate the mass, velocity or momentum of objects

    18. Use force = change in momentum ÷ time taken, F = Δp/t = (mv − mu)/t.

    19. Demonstrate an understanding of Newton’s third law

    20. Know and use moment = force × perpendicular distance from the pivot.

    21. Know that the weight of a body acts through its centre of gravity

    22. Use the principle of moments for a simple system of parallel forces acting in one plane

    23. Understand how the upward forces on a light beam, supported at its ends, vary with the position of a heavy object placed on the beam