Forces

• Saclar - magnitude (size only)

  Vector - magnitude & direction
• Force - a push or pull acting on an object interacting with another object
• Contact force - force that’s physically touching the object
• Non contact - isnt physically touching the object
• Weight is the force acting on an object due to gravity. The force of gravity close to earth is due to gravitational field around the earth.
• weight = mass x gravitational field strength
• Resultant force – the number of forces acting on an object
• A single force can’t be resolved into two components acting on the right angle of each other. The two components of forces still have the same effect as the one single force
• Work done – when a force causes an object to move through a distance, work is done on the object
• Work done = force x distance moved (J)
• Describe the energy transfer involved when work is done

  Work done involves transferring energy as energy is transferred From the force to the object
• Explain why to change the shape of an object by stretching, bending or compressing more than one force has to be applied- this is limited to stationary objects


  More than one force has to be applied to change the shape of a stationary object as a single force would simply caused the object to move in the direction which the forces been applied
• Elastic deformation matter how much you stretch the force, it will return back to its original state
• An elastic material, when stretch, it does not go back to its original state when forces are removed
• Force = spring constant x extension
• Displacement - a vector quantity both the distance and object moves, measured in a straight line from the start point to the finish point
• Typical values of speed

  • walking - 1.5m/s
  • running - 3m/s
  • cycling - 6m/s
• typical values of speed

  • car on road - 13m/s
  • train in uk - 50m/s
  • speed of sound in air - 330m/s
• speed does not include direction, making it a scalar whereas velocity as the velocity of an object, is the speed given in a direction
• Newtons laws of motion described that affect that forces have on the motion of an object
• Newton third law - whenever two objects interact, the forces they exert on each other are equal & opposite
• Newton’s first law - if the result of force on an objective, zero if the object is stationary, it will stay stationary. If the object is moving, it will keep moving in the same speed and same direction and so the object continues to move in the same velocity.
• Inertia - the tendency of an object to continue in the stay or keep the same motion unless resultant force is being applied
• Newton’s second law - the acceleration of an object is proportional to the result of force and an inversely proportional to the mass
• Resultant force = mass x acceleration
• internal mass is a measure of how difficult it is to change the velocity of an object. Internal mass is defined as the ratio of force over acceleration.
• Affects of reaction time

  • being tired
  • Taking drugs or alcohol
• Affects of breaking distance

  • Wet conditions on the road
  • Car has worn tyres
  • worn brakes
• Large decelerations may cause, breaks, overheating & or lose control
• Resistant forces causes cars to decelerate
• Momentum = mass x velocity
• A total momentum before the collision is equal to the total momentum after the collision