Kinetic Energy (Eₖ)
- Kinetic energy (Ek) is the energy an object has due to its motion (or velocity)
- The faster an object is moving, the greater its kinetic energy
- When an object is falling, it is gaining kinetic energy since it is gaining speed
- This energy transferred from the gravitational potential energy it is losing
- An object will maintain this kinetic energy unless its speed changes
Kinetic energy (KE): The energy an object has when its moving
Derivation of Kinetic Energy Equation
- A force can make an object accelerate; work is done by the force and energy is transferred to the object
- Using this concept of work done and an equation of motion, the extra work done due to an object's speed can be derived
- The derivation for this equation is shown below:
Worked example
A body travelling with a speed of 12 m s-1 has kinetic energy 1650 J.If the speed of the body is increased to 45 m s-1, what is its new kinetic energy?
Examiner Tip
In your exam, you will be expected to know how to derive the kinetic energy equation from first principles, so make sure to practice this derivation!
