We think you are located in South Africa. Is this correct?

Chapter Summary

Don't get left behind

Join thousands of learners improving their science marks online with Siyavula Practice.

Sign up here

Chapter summary

Presentation: VPfvd

  • The gravitational potential energy of an object is the energy the object has because of its position in the gravitational field relative to some reference point.

  • The kinetic energy of an object is the energy the object has due to its motion.

  • The mechanical energy of an object is the sum of the potential energy and kinetic energy of the object.

  • The unit for energy is the joule (\(\text{J}\)).

  • The Law of Conservation of Energy states that energy cannot be created or destroyed, but can only be changed from one form into another.

  • The Law of Conservation of Mechanical Energy states that the total mechanical energy of an isolated system (i.e. no friction or air resistance) remains constant.

  • The table below summarises the most important equations:

Potential Energy

\({E}_{P}=mgh\)

Kinetic Energy

\({E}_{K}=\frac{1}{2}m{v}^{2}\)

Mechanical Energy

\({E}_{M}={E}_{K}+{E}_{P}\)

Physical Quantities

Quantity

Unit name

Unit symbol

Potential energy (\({E}_{P}\))

joule

J

Kinetic energy (\({E}_{K}\))

joule

J

Mechanical energy (\({E}_{M}\))

joule

J

Table 22.1: Units used in mechanical energy