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physics exam revsion - Coggle Diagram

- - - - the extension is directly proportional to the force applied.
        
        stopping distance = thinking distance + braking distance
        
        thinking distance is the distance a vehicle travels in the time it takes for the driver to apply the brakes after realising they need to stop
        braking distance is the distance a vehicle travels in the time after the driver has applied the brake
        
        A driver's reaction time can be affected by:
        
        tiredness
        
        drugs
        
        alcohol
        
        distractions
        
        When a force is applied to the brakes of a vehicle, there is work done by the friction between the brakes and the wheel. This reduces the kinetic energy of the vehicle, slowing it down and causing the temperature of the brakes to increase.
        
        The braking distance of a vehicle can be affected by:
        
        poor road and weather conditions, such as wet or icy roads
        
        poor vehicle conditions, such as worn brakes or worn tyres
        
        The faster a vehicle travels, the greater the braking force needed to stop it in a certain distance. A greater braking force produces a greater deceleration
- - - - frequency - the number of waves passing a point each second
        
        time period = 1/frequency
        
        The particles move up and down as the wave is transmitted through the medium.
        
        Examples of longitudinal waves include:
        
        sound waves
        
        ultrasound waves
        
        Longitudinal waves show areas of compression and rarefaction:
        
        compressions are regions of high pressure due to particles being close together
        
        rarefactions are regions of low pressure due to particles being spread further apart
        
        they move backwards and forwards between compressions as the wave is transmitted through the medium.
        
        examples of transverse waves
        -seismic waves
        -ripples on surface of water
        -vibrations of guitar string
        
        Electromagnetic waves are transverse waves. Their vibrations or oscillations are changes in electrical and magnetic fields
        
        transfer energy as radiation from the source of the waves to an absorber
        
        can travel through a vacuum such as in space
        
        travel at the same speed through a vacuum or the air
        
        Ultraviolet waves, X-rays and gamma rays are types of ionising radiation. They can add or remove electrons from molecules, producing electrically charged ions. Ionisation can have hazardous effects
        
        ultraviolet waves can cause skin to age prematurely and increase the risk of skin cancer
        x-rays and gamma rays can cause the mutation of genes, which can lead to cancer
        
        Background radiation is all around us, all the time. Sources include:
        
        radioactive rocks in the Earth's crust
        
        cosmic rays from space
        
        man-made sources such as nuclear weapons fallout and nuclear accidents
- - - - Acceleration is the rate of change of velocity. It is the amount that velocity changes per unit time.
      - At terminal velocity, the object moves at a steady speed in a constant direction because the resultant force acting on it is zero.
        
        :
        
        According to Newton's First Law, an object remains in the same state unless a resultant force acts on it. If the resultant force on an object is zero, this means:
        
        resultant force = mass × acceleration
        
        a stationary object stays stationary
        
        a moving object continues to move at the same velocity (at the same speed and in the same direction)