Kinetic Energy (DP IB Physics: SL): Revision Note

Kinetic Energy

• Kinetic energy (E_k) is the energy an object has due to its motion (i.e. because it's moving)

  • The faster an object is moving, the greater its kinetic energy

• When an object is falling, it is gaining kinetic energy since it is accelerating under gravity

• This energy is transferred from the gravitational potential energy it is losing

• An object will maintain this kinetic energy unless its speed or mass changes

• Kinetic energy can be calculated using the following equation:

$E_k=\frac{1}{2}m{v}^2$

• Where:

  • E_k = kinetic energy (J)

  • m = mass (kg)

  • v = velocity (m s^–1)

Kinetic energy: The energy an object has when it is moving

• Another quantity that also depends on mass m and velocity v is momentum

• Therefore, kinetic energy can be written in terms of momentum p, using the equation

$E_k=\frac{p^2}{2m}$

• Where:

  • p = momentum (kg m s^–1)

• This form is very useful in particle physics, when comparing the momentum and kinetic energy of a particle