Paper 2

• a vector is a quantity that has both magnitude and direction, and is used to represent displacement
• a scalar is a quantity that only has magnitude and no direction, such as speed or distance
• newtons third law states that for every action there is an equal and opposite reaction
• resultant force is a single force that has the same effect as all the forces acting on an object
• newtons first law of motion states that if the forces acting on an object are balance then the resultant force is zero
• newtons second law states that for every action there is an equal and opposite reaction
• centre of mass of an object is the point where its mass can be thought as being concentrated
• parallelogram of forces is a scale diagram of 2 force vectors and is used to find the resultant of 2 forces that do not act along the same line
• for an object to be equilibrium the resultant force must be zero
• gradient of a distance time graph represents the speed of an object
• displacement means the distance travelled in a direction
• velocity is speed in a given direction
• deceleration is the change of velocity per second when an object slows down
• independent variable is the one you change
• dependant variable is the one you measure
• control variable is the one you keep the same
• on a velocity time graph a positive gradient represents acceleration but a negative gradient represents deceleration
• inertia means that an object will continue in its current state of motion unless acted upon by an external force
• investigating force and acceleration

  1. hang mass with hook over edge attached to cart
  2. add masses to the holder gradually until the trolley moves
  3. record results
  4. repeat experiment
• weight of an object is the force acting on the object due to gravity
• the terminal velocity of an object is the velocity it eventually reaches when its falling
• thinking distance is the time taken to react to a hazardous situation
• stopping distance is the distance travelled by a vehicle from the time it starts to stop until it comes to a complete stop
• braking distance is the distance travelled by a vehicle from the time it starts to brake until it comes to a complete stop
• factors affecting stopping distance

  • tiredness
  • drugs
  • speed of vehicle
• friction and air resistance slow a vehicle down
• poor weather conditions increase the breaking distance
• conservation of momentum is the total momentum of an object before an event is equal to the total momentum of the object after the event
• elasticity practical

  1. attach spring to the clamp stand and hang it off the clamp
  2. hold ruler vertically
  3. measure length of spring with the weights on
  4. add 50g mass each time and measure the spring extension
• transverse waves are waves that oscillate perpendicular to the direction of energy transfer
• longitudinal waves oscillate parallel to the direction of energy transfer
• amplitude is the maximum displacement of a point on the wave
• wavelength is the distance from one wave crest to the next wave crest
• frequency of a wave is the number of waves per second
• refraction occurs at a boundary between 2 different materials because the speed and wavelength of the waves change
• investigating waves practical

  1. attach the spring to the vibration generator that is passed over the pulley and held with a mass hanging
  2. measure length of each string
  3. turn on signal generator
  4. increase frequency until you see a wave
• electromagnetic spectrum

  1. radio waves
  2. microwaves
  3. infrared
  4. visible light
  5. ultraviolet
  6. x rays and gamma radiaton
• infrared radiation is used for carrying signals from remote controls hansets and inside optical fibres
• microwaves have a shorter wavelength than radio waves
• absorption and emission of infrared radiation practical

  1. put 2 thermometers in 2 cans that are different colours
  2. measure how fast each can heats up