physics paper 2

• gravitational field strength

  gravity exerted around an object
• scalar quantity

  a quantity that has only magnitude. For example mass, time, speed, temperature
• vector quantity

  a quantity that has magnitude and direction. For example force, velocity, momentum
• mass

  the amount of matter
• weight

  force acting on an object due to gravity
• up thrust

  resultant force exerted by a fluid pushing an object up
• hydraulic machine

  uses liquid to transmit pressure
• atmospheric pressure

  caused by billions of air particles colliding with a surface
• contact force

  exerted between 2 objects when they touch. For example friction, air resistance, tension
• non contact force

  exerted between 2 objects without touching. For example gravity, electrostatic forces, magnetic forces
• resultant force

  the overall effect of all of the forces acting upon an object
• resolving force

  an object pulled with a force at an angle. A single force can be split into 2 components acting at right angles to each other
• work done

  when work is done energy is transferred
• elastic deformation

  the object has been stretched but returns to its original length
• inelastic deformation

  the object has been stretched but does not return to its original length
• newtons first law

  when the resultant force of a still object is 0 then the object is stationary

  when the resultant force of a moving object is 0 then the object is at a constant speed
• newtons second law

  when the resultant force is greater than 0 then the object accelerates. It could speed up slow down or change direction
• newtons third law

  when 2 objects interact the forces exerted are equal and in opposite direction
• inertia

  when object continue in the same state of motion
• terminal velocity

  the weight of an object is balanced by resistive forces
• falling objects

  falling objects accelerate due to gravity air resistance slows down falling objects but if there is no air resistance then the objects accelerate at 9.8m/s2
• thinking distance

  the distance travelled whilst the driver reacts
• braking distance

  the distance travelled whilst the car is stopped by the brakes
• stopping distance

  the total thinking distance and breaking distance
• inertia mass

  how difficult it is to change the velocity of an object. If the mass is large, to change velocity a big force is needed
• conservation of momentum

  when 2 objects collide the momentum they have before the collision is the same as the momentum they have after the collision
• factors that affect stopping distance

  the drivers reaction time (drinking alcohol, taking drugs, tired) the breaking distance (weather conditions, worn tyres, road surface)
• braking and kinetic energy

  work done by breaking balls, reduces kinetic energy. when kinetic energy decreases, temperature of brakes increases due to frictional forces
• wavelength

  the distance from 1 point of the wave to the same point on the next wave
• amplitude

  the maximum disturbance from its rest position
• frequency

  number of waves per second
• period

  the time taken to complete 1 wave
• reflection

  wave bounced off the surface
• refraction

  wave changes direction at boundary
• transmitted

  passes through the object
• absorbed

  passes into but not out of the object, transfers energy and heats up the object
• transverse wave

  vibrations causing the wave is a right angle to the direction of energy transfer energy is carried outwards by the wave
• longitudinal waves

  vibrations causing the wave is parallel to the direction of energy transfer energy is carried along the wave
• black body radiation

  all objects absorb over flight infrared radiation
• constant temperature

  where the rate of absorption is the same as the rate of reaction