How Do Everyday Machines Turn Energy Into Work?

Everyday machines are super important in our lives. They help change energy into work. If you are in Year 7 and learning about energy and work in science, understanding this change is essential.

What Are Energy and Work?

• Energy is what makes it possible to do work. It comes in different types, like mechanical, thermal, electric, and chemical energy.

• Work happens when a force moves something over a distance. The way to calculate work is:

  $$W = F \times d$$

  Here, ( W ) is work measured in joules (J), ( F ) is force measured in newtons (N), and ( d ) is distance measured in meters (m).

How Energy Changes Form

Machines often change one kind of energy into another. Here are some common changes:

1. Mechanical Energy to Electrical Energy:

   • For example, wind turbines take energy from the wind and turn it into electrical energy. This electricity can power homes and businesses. One turbine can make about 1.5 to 3 megawatts (MW) of energy, which is enough to support about 500 to 1,000 homes.

2. Chemical Energy to Mechanical Energy:

   • Cars burn gasoline to change chemical energy into mechanical energy. An average car engine is only about 20% efficient. This means only 20% of the fuel's energy is used to do work.

3. Electrical Energy to Mechanical Energy:

   • Electric motors, found in things like washing machines and fans, change electrical energy into mechanical energy. A standard washing machine uses about 0.3 to 2 kWh of electricity for one cycle.

How We Use Energy and Work in Real Life

Learning how machines change energy helps us see how they affect our daily lives. Here are some examples:

• Household Appliances:

  • Refrigerators use electrical energy to keep food cold. A regular fridge uses about 100 to 800 kWh each year.

• Transportation:

  • Public transport, like trains, uses electric energy. A light rail train can carry around 200 passengers each trip and uses about 3 to 4 kWh for every mile.

• Construction Equipment:

  • Big machines like cranes and excavators use electric or fuel energy to move heavy stuff. A large crane can lift loads weighing up to 50 tons.

How Well Do Machines Work?

The efficiency of a machine tells us how well it changes energy into useful work. We can figure out efficiency with this formula:

$$\text{Efficiency} (\%) = \left( \frac{\text{Useful Work Output}}{\text{Total Energy Input}} \right) \times 100$$

For example:

• A regular electric motor works at about 90% efficiency. This means it turns 90% of the electric energy into mechanical work.

• Car engines usually have efficiency levels between 20% and 30%.

Wrapping It Up

Everyday machines are very important for turning energy into work, which impacts our lives a lot. Understanding how energy and work relate helps us see how machines play a role in our daily activities. By knowing how efficient these machines are and how they are used, we can make smart choices about using energy and its effects on our environment.