The idea of "work done" is closely related to how energy is saved or changed in physics. This is especially important when you're in Year 9 studying these concepts. Work is all about moving energy, and it helps us see how energy is kept in different situations.

What is Work?

Work can be calculated using this formula:

$$W = F \times d \times \cos(\theta)$$

Let’s break this down:

• $W$ means work done
• $F$ is the force applied, measured in Newtons (N)
• $d$ is the distance the force is applied over, measured in meters (m)
• $\theta$ is the angle between the force and the way the object is moving

How Work Relates to Energy

When you do work on something, you give it energy. This energy can be in different forms:

• Kinetic Energy: This is the energy of moving things. When you do work on an object, it starts to move faster. We can write it like this:

$$KE = \frac{1}{2} mv^2$$

Here, $m$ is the mass of the object in kilograms (kg), and $v$ is its speed in meters per second (m/s).

• Potential Energy: This is the energy stored in an object because of its position. If you lift something against gravity, the work you do helps it gain potential energy, calculated by:

$$PE = mgh$$

In this formula, $h$ is how high you lift the object (in meters), and $g$ is the pull of gravity, which is about $9.81 \, \text{m/s}^2$.

Keeping Energy Safe

The conservation of energy tells us that energy can’t be made out of nothing or disappear. It can only change from one form to another. So, all the work you do on a system is equal to the change in its energy:

$$\text{Total Work Done} = \Delta KE + \Delta PE$$

In simple terms, knowing about work and how to calculate it helps you understand how energy changes and is saved in Year 9 physics.