Lesson 1: Simple Machines and their Purposes

Video Lesson:

Competencies (MLC):

At the end of this section, you should be able to:

• Define simple machines.
• Identify simple machines as a force multiplier, distance multipliers or direction changers.
• List different simple machines in your locality.

Brainstorming Question

What type of simple machines do you use in your home?

key terms and concepts

Simple Machines and their Purposes

Imagine trying to staple a stack of papers with your bare hands—it’s nearly impossible and dangerous. A stapler makes this task quick, easy, and safe by using a simple machine, which requires just one force to do mechanical work. Like a stapler, many systems use one or more simple machines to make tasks like nailing, cutting, or carrying much easier.

Simple machines are devices that transfer energy, making mechanical work easier by:

• Changing the direction of force: For example, pulling down on a rope to raise a flag on a flagpole.
• Changing the distance of effort (to multiply speed or distance): Carrying a heavy box up an inclined plane, such as stairs, increases the distance over which you apply force but reduces the effort needed.
• Changing the strength of a force (to multiply force): Using a bottle opener, a small force applied over a long distance is magnified to exert a greater force on the bottle cap.

Though simple machines make tasks easier, they don’t reduce the total work done. If a machine increases force, the distance over which that force is applied decreases, and vice versa. Simple machines require energy, often supplied by you through pushing or pulling, or by other sources like gasoline or electricity. The energy you apply is the input, while the machine’s effect is the output. The total energy input and output remains the same because simple machines act as force or speed multipliers.

• Effort (F): The force you apply to a machine, like pushing a lever.
• Load (L): The force the machine applies to move or lift an object.

Mechanical work requires moving the effort through a distance (work input), and the machine moves the load (work output).

if, we neglect friction, the total energy and output remains the same because a simple machine acts as a force or speed multiplier. Or   in real machine there is loss of energy due to external forces such as friction, hence the output energy is always less than the total input energy.