physics 1

• Kinetic energy is the energy stored in moving objects, such as a ball rolling down a hill.
• The kinetic energy equation

  Kinetic energy(J)= 0.5 x mass(kg) x speed^2(m/s)
• when we stretch a spring we're applying a force to change the length of the spring
• Elastic Potential Energy = ½ x Spring Constant (N/m) x Extension Length² (m)
• gravitational potential energy is the energy stored in an object due to its position above the earths surface due to the force of gravity acting on an object
• gravitational potential energy equation

  gpe= m x g x h (mass(kg) x gravitational field strength(N/kg) x height (m)
• The specific heat capacity of a substance is the amount of energy needed to raise the temperature of 1kg of the substance by 1 degree
• spc equation


  change in thermal energy=mass x specific heat capacity x temperature change
• The law of conservation of energy = energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.
• A system is an object or group of objects
• in a closed system no energy can enter or leave
• friction causes energy to be transferred to thermal energy
• to reduce unwanted energy transfers you can use a lubricant e.g oil on the fixed point and removing air particles around the pendulum
• work is done whenever energy is transferred from one store to another
• work done equation

  work done (J)= force(N) x distance(m)
• power is the rate at which energy is transferred or the rate at which work is done
• power(W)= work done (J)/ time (s) or energy transferred(J)/time(s)
• 1 watt is an energy transfer of 1 J per second
• efficiency = useful output energy transfer/total input energy transfer or useful power output/ total power input