Physics. Forces

• Work done = force x distance moved in direction of force
• Energy can be transferred from one object to another by work done or heat transfer.
• The SI unit of energy is the joule (J).
• Energy can be stored as potential energy when an object is raised above ground level.
• The law of conservation of energy states that the total amount of energy is constant, it cannot be created nor destroyed but only transformed into different forms.
• Potential energy (PE) is stored energy within an object due to its position or shape.
• Kinetic energy (KE) is the energy an object has due to its motion.
• Kinetic energy is the energy that an object has due to its motion, given by half mass times velocity squared.
• Heat energy is the total kinetic energy of all particles within an object.
• Potential energy is stored energy due to position or shape.
• Kinetic energy is energy associated with motion.
• Elastic potential energy is stored in stretched springs or deformed objects.
• Elastic potential energy is energy stored in stretched springs.
• Work done is defined as force multiplied by distance moved in the direction of the force.
• The law of conservation of energy states that energy cannot be created or destroyed, only transferred from one form to another.
• work


  The energy transferred when a force moves an object. It is calculated using the size of the force and the distance moved by the force. The unit for work is the joule (J).

  
• pulley


  A simple machine consisting of a wheel that can turn on an axis with a rope running around it. Using more than one pulley with a rope allows a force to be multiplied.

  
• ramp


  A sloping surface. A ramp is a force multiplier: it needs less force to pull something up a ramp than it does to lift it directly.

  
• machine


  A device, such as a lever or ramp, that makes it easier to move something by multiplying a force or a distance.

  
• pivot


  A point about which something turns. Another name for fulcrum.

  
• newton metre (N m)


  The unit for the moment of a force.
• moment


  The turning effect of a force. It is calculated by multiplying the force by the perpendicular distance of the force from the pivot.
• load


  The weight or force on something. For a machine, the load is the weight that is being moved.
• lever


  A simple machine that consists of a long bar and a pivot. It can increase the size of a force or increase the distance the force moves.

  
• in equilibrium

  In balance.
• fulcrum


  A point about which something turns. Another name for a pivot.

  
• force multiplier


  A lever or other machine where the load is bigger than the effort.
• effort


  The force put on something, especially a lever or other simple machine.
• distance multiplier


  A lever or other machine where the load moves further than the effort.
• gradient


  A way of describing the steepness of a line on a graph in numbers. It is calculated by taking the vertical distance between two points and dividing by the horizontal distance between the same two points.
• speed


  How fast something is moving. Often measured in metres per second (m/s), miles per hour (mph) or kilometres per hour (km/h).
• relative speed


  The speed of one object compared to another - both objects could be moving.
• miles per hour (mph)


  Unit for speed when the distance is measured in miles and the time is measured in hours.
• metres per second (m/s)

  Unit for speed when the distance is measured in metres and the time is measured in seconds.
• kilometres per hour (km/h)


  Unit for speed when the distance is measured in kilometres and the time is measured in hours.
• distance-time graph

  A graph that shows how far and how fast something travels during a journey. Steeper lines on the graph show faster speeds.

  
• mean speed


  The total distance something travels divided by the total time taken is the mean (or average) speed for a journey.
• thermal energy


  A name used to describe energy when it is stored in hot objects. The hotter something is the more thermal energy it has.
• strain energy

  A name used to describe energy when it is stored in stretched or squashed things that can change back to their original shapes. Another name for elastic potential energy.
• sound


  A way of transferring energy by waves. Sound waves travel through substances. They cannot travel through a vacuum.