This page will discuss some of the most frequently asked questions about the topic.

Do you need to remember all the definitions?

In short, yes. Learning the definitions will help you remember the formulae (and vice-versa). This goes hand in hand with the question of "Do you need to remember all the formulae". The formulae sheet is very limited so it is useful to all ready be familiar with the formulae.

Is energy always a scalar quantity?

Although some energy equations contain variables that are vector quantities (e.g Kinetic energy with velocity), Energy is always a scalar quantity.

How do you know which unit for Work to use?

When in doubt, use joules as it is the least confusing. Unless the question states otherwise joules can be used for any form of energy including Work. It is useful to know how to derive the other units in case you are asked or a question tries to mislead you to think the question is not about work or energy.

Must you remember all the types of energy?

No, as long as you remember the two main categories, kinetic and potential, and how to delegate different forms into those groups. It's also useful to know the common examples of "wasted energy" or energy categorised as a loss, for when drawing sanky diagrams and answering questions. Heat and sound energy are common examples.

Can you use only one of the power equations?

You need to be comfortable with using both equations because questions can expect to manipulate both in order to achieve an answer. You may be only given velocity and a distance and expected to figure out the time taken.

Is efficiency always given as a percentage?

More often than not the question will state what it wants it as, if not then either will be fine but a percentage is most common to leave efficiency as.