AQA Physics 2 (PART 1)

Forces and Their Affects
1. Resultant force
  1. whenever two objects interact, the forces they exert on each other are equal and opposite
    1. a resultant force acting on an object may cause a change it its state of rest or movement
      1. if the resultant force is acting on a stationary object is 1) ZERO, the object will remain stationary 2)NOT ZERO, the object will accelerate in the direction of the resultant force
      2. if the resultant force acting on a moving object is: 1)ZERO, the object will continue to move at the same speed and in the same direction 2)NOT ZERO, the object will accelerate in the direction of the resultant force
2. Forces and Motion
  1. the acceleration of an object is determined by the resultant for acting on the object and the mass of the object
    1. F=Resultant Force (N) m= Mass (Kg) a=Acceleration (m/s^2)
    2. The gradient of a Distance-Time Graph represents speed
    3. HIGHER TIER
      1. The VELOCITY of an object is its speed in a given direction
      2. The gradient of a Velocity-Time graph represents acceleration
        a= Acceleration (m/s^2) v=Final Velocity (m/s) u= Initial Velocity (m/s) t= Time Taken (s)
        YOU NEED TO BE ABLE TO: 1) calculate acceleration from the graph 2) calculate distance travelled on the graph
3. Forces and Braking
  1. when a vehicle travels at a steady speed, the resistive forces balance the driving force (most resistive forces are caused by AIR RESISTANCE)
    1. the greater the speed of a vehicle the greater the braking force needed to stop it in a certain distance
      1. THE GREATER THE SPEED, THE GREATER THE BRAKING DISTANCE
      2. The stopping distance of a vehicle is the sum of the distance the vehicle travels during the driver's reaction time (thinking distance) and the distance it travels under the braking force (braking distance).
        A driver's reaction time can be affected by tiredness, drugs and alcohol
        When the brakes of a vehicle are applied, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increase.
        A vehicle's braking distance can be affected by adverse road and weather conditions and poor condition of the vehicle.
        'adverse road conditions' includes wet or icy conditions. Poor condition of the car is limited to the car's brakes or tyres.
4. Forces and Terminal Velocity
  1. The faster an object moves through a fluid the greater the frictional force that acts on it.
    1. An object falling through a fluid will initially accelerate due to the force of gravity. Eventually the resultant force will be zero and the object will move at its terminal velocity (steady speed).
  2. the use of a parachute reduces the parachutist's terminal velocity.
    1. YOU MUST BE ABLE TO: Draw and interpret velocity-time graphs for objects that reach terminal velocity, including a consideration of the forces acting on the object
    2. Calculate the weight of an object using the force exerted on it by a gravitational force:
      1. W=Weight (N) m= Mass (kg) g= Gravitational field strength (Newtons per kilogram = N/kg)
5. Forces and Elasticity
  1. A force acting on an object may cause a change in shape of the object.
    1. A force applied to an elastic object such as a spring will result in the object stretching and storing elastic potential energy.
      1. For an object that is able to recover its original shape, elastic potential energy is stored in the object when work is done on the object to change its shape.
        The extension of an elastic object is directly proportional to the force applied, provided that the limit of proportionality is not exceeded
        F= Force (N) k= 'spring constant' (Newtons per metre, N/m) e= Extension (m)
        F = k × e
The kinetic energy of objects speeding up or slowing down
1. When an object speeds up or slows down, its kinetic energy increases or decreases. The forces which cause the change in speed do so by doing work. The momentum of an object is the product of the object's mass and velocity.
2. Forces and Energy
  1. When a force causes an object to move through a distance work is done.
    1. Work done, force and distance are related by the equation:
      1. Energy is transferred when work is done.
  2. Discuss the transfer of kinetic energy in particular situations. Examples might include shuttle re-entry or meteorites burning up in the atmosphere.
  3. Power is the work done or energy transferred in a given time (work=energy)
  4. Gravitational potential energy is the energy that an object has by virtue of its position in a gravitational field.
    1. Ep = m x g x h
      1. Ep = The change in Gravitational Potential Energy (joules, J). m = The Mass (kilograms, kg). g = The Gravitational Field Strength (Newtons per kilogram, N/kg). h = The change in Height (metres, m)
        The Gravitational Field Strength on EARTH is 10 N/kg
  5. The kinetic energy of an object depends on its mass and its speed
3. Momentum
  1. Momentum is a property of moving objects
    1. p = momentum (kilograms metres per second, kg m/s). m = the mass (kilograms, kg). v = the velocity (metres per second, m/s)
    2. In a closed system the total momentum before an event is equal to the total momentum after the event. This is called conservation of momentum.
    3. Candidates may be required to complete calculations involving two objects. Examples of events are collisions and explosions.
FIRST THREE SECTIONS
Currents in electrical circuits
1. The current in an electric circuit depends on the resistance of the components and the supply.
2. Static electricity
  1. When certain insulating materials are rubbed against each other they become electrically charged. Negatively charged electrons are rubbed off one material and onto the other

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AQA Physics 2 (PART 1)

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