physics - energy

• Work is done whenever energy is transferred.

  Work done = energy transferred
• work ( J ) = force ( N ) x distance moved ( M )
• Kinetic energy (J) = ½ x mass (kg) x (velocity (m/s))²
•  Change in gravitational potential energy (J) = mass (kg) x Gravitational field strength (N/kg) x Change in height (m)
• “Energy can be transferred, stored, or dissipated, but can NEVER be created or destroyed.”
• Power is the rate at which work is done
• power = work done $\div$ time
• power = energy transferred $\div$ time
• • The unit of power is “watt” (W)
• • Work done is measured in joules (J)
• • Time is measured in seconds (s).
• Hooke’s Law

  The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.
• The spring constant k is sometimes called the stiffness
• • Once you pass the elastic limit, you will deform or stretch the material.
• Elastic Energy

  • A force acting on an object may cause the shape of an object to change.
• • Elastic objects can store elastic potential energy if they are stretched. 
• • Elastic potential (J) = ½ x Stiffness constant k (N/m) x (extension(m))²