Physics GCSE Module 2

Physics GCSE - Module 2

  • Created by: Louisa
  • Created on: 18-05-12 19:29

Forces - 1

  • Force = mass x acceleration
  • Gravity, magnetism and electrical charges cause forces
  • Measured in newtons
  • Measured with a newtonmeter
  • Can push or pull
  • Forces affect the movement of an object
  • If the forces acting on an objest are equal (or balanced) then the object will stay as it is
  • If the forces acting on an object are unequal (or unbalanced) then the object will move

Newtons Ideas

Newton sorted out a lot of ideas about foces and produces three laws:

  • When one object exerts a force on another, the second object exerts an equal and opposite force on the first (often called  a newton pair)
  • When the forces on something are balanced, it stays still or it keeps moving with a constant velocity (same speed in a straight line)
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Forces and Speed

If the forces are unbalanced the velocity will change.

  • A stationary object accelerates in the direction of the force
  • A moving object speeds up, slows down or changes direction, depending on the unbalanced (or resultant) force


  • Speed = distance / time

Distance / Time graph

  • Straight line = steady speed
  • Steep line = fast
  • Horizontal line = stopped / stationary
  • Gently gradient = slow
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Acceleration and Decceleraton

  • When the speed of something moving increases, we say it accelerates
  • When it slows down we say it deccelerates
  • A change in direction also counts as acceleration, because the velocity is changed
  • To calculate the acceleration we work out how much the speed increases each second
  • Acceleration = change in velocity / time taken
  • A straight line graph through the origin shows that the acceleration is directly porportional to the force
  • A (alpha) F means porportional to
  • 1 newton is the force that makes 1kg accelerate at 1m/s squared
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Velocity / Time Graphs


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Road Safety

When a driver sees a hazard she takes a short time to react (about 0.7s) and then does an emergency stop.

  • The thinking distance, which is how far the vehicle travels as the driver reacts
  • The breaking distance, which is how far the vehicle travels as is slows to a stop
  • Thinking distance is increased be tiredness, alcohol (and other drugs), and distractions.
  • Breaking difference is increased if the road is wet, or icy, or if the vehicle has worn breaks or worn tyres
  • Speed also makes a difference
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Spring Behavior, Hookes Law and Kinetic Energy

Spring behavior

  • A spring is a good example of elastic behavior, it stretches when loaded, and returns to its original length when the load is removed

Hookes law

  • Hookes law is F = k x e (F = force, k = constant, and e = extention)

Kinetic Energy

  • Kinetic energy is the energy a moving object has
  • It depends on the mass and the speed
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Gravitational Potential Energy and Momentum

Gravitational Potential Energy

When things are lifted up, they gain gravitational potential energy. When they fall they lose their gravitational potential energy.

  • To work out the gravitational potential energy gained we use: Gravitational Potential Energy = Weight x Height Gained (J = N x m)
  • Also Weight = Mass x Gravitational Field Strength (N = kg x N)


  • Momentum = mass x velocity (kg m/s = kg x m/s)
  • We cannot make it or get rid of it - we can only transfer it
  • Momentum before the event = momentum after the event
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I quite like it!

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