phys defs

• stopping distance = thinking distance + breaking distance
• breaking and stopping distance increase with speed
• when the breaks are used the temperature of the brakes increases. why, use ideas of energy


  -there is a decrease in the kinetic energy of the car -this causes the thermal energy of the breaks to increase
• use of drugs increases the thinking distance
• velocity is speed with a direction
• to find the gradient of a curved line draw a tangent from it
• the typical speed of a person walking is 1.5 m/s.
• The typical speed of a person running is 3 m/s
• The typical speed of a person cycling is 6 m/s
• The typical speed of a car is 25 m/s
• The typical speed of a train is 55 m/s
• typically, the speed of an aeroplane is 250 m/s
• The wavelength of light emitted from distant galaxies is different when the light is detected on Earth. Explain how this difference in wavelength shows that the Universe is expanding:

  -increase in space between galaxies

  -therefore loner wavelength

  -shows galaxies are moving further away from earth
• direct potential difference is potential difference with a fixed polarity
• Eventually, the particles vibrate fast enough to break the intermolecular bonds and move randomly in an irregular, liquid, arrangement.
• the upward force of friction (air resistanc) eventually balances out the downward force of gravity and causes acceleration to stop
• the upward force of friction (air resistanc) eventually balances out the downward force of gravity and causes acceleration to stop
• velocity is a vector
• mains electricity is an alternating current
• alternating current has a frequency of 50 hertz
• alternating current has a potential difference of 230 volts
• in a direct current potential difference doesn’t change
• the live wire can be fatal if touched
• if the live wire comes loose the appliance can become live and potential difference is transferred to it
• the earth wire is connected into the ground and current can flow to the earth
• What do step-up transformers do?

  They increase the potential difference
• How do step-up transformers affect energy loss in transmission cables?

  They reduce energy loss in the transmission cables
• What is the function of step-down transformers?

  They reduce the potential difference
• What are the roles of step-up and step-down transformers in electricity transmission?

  • Step-up transformers:
  • Increase potential difference
  • Reduce energy loss in transmission cables
  • Step-down transformers:
  • Reduce potential difference
  • Prepare electricity for home use