Print Friendly, PDF & Email
A man and a girl on a seesaw

Types of lever: What kind of lever is a see-saw?

Three types of lever

All levers fall into one of three types of lever. How can we tell which lever is in which class? The main difference is what order the different parts come in. Every lever has three parts: the force, the fulcrum, and the weight.

Introduction to levers
More about simple machines
All our physics articles

What is a first-class lever?

Well, a first-class lever is a stick where the fulcrum is in between the weight and the energy or force moving the weight (your hands, for example). There’s something pushing or pulling on one side, something pushing or pulling on the other side, and a fixed point in the middle. So the order of a first-class lever is force-fulcrum-weight.

What’s an example of a first-class lever?

Some common first-class levers are see-saws, crowbars, and pliers. A pair of scissors (which use two first-class levers together), and a hammer pulling a nail out of a board are also first class levers. A wheel is also a kind of first-class lever.

More about wheels
When were see-saws invented?

A man pushing some kids in a wheelbarrow

What kind of lever is a wheelbarrow?

And then a second-class lever is a stick where the fulcrum is at one end of the stick and you push on the other end. The weight is in the middle of the stick. So the order of a second-class lever is fulcrum-weight-force.

What’s an example of a second-class lever?

Some common second-class levers are doors, staplers, wheelbarrows, and can openers.

More about wheelbarrows

A woman playing softball

What kind of lever is a baseball bat?

So then what is a third-class lever?

A third-class lever is a stick where the fulcrum is at one end of the stick, you push on the middle, and the weight is at the other end of the stick. The order of a third-class lever is fulcrum-force-weight.

With a third-class lever, you have to put in more energy than you would just lifting the weight. But you get the weight to move a longer distance in return.

What’s an example of a third-class lever?

Some common examples of third class levers are a broom, a hoe, a fishing rod, a baseball bat (or a cricket bat), and our own human arms. Your jaw is a third-class lever. A bow and arrow is also a third-class lever.

More about bows and arrows
The evolution of jaws

Learn by doing: Find examples of each kind of lever that aren’t mentioned here
More about simple machines

Bibliography and further reading about simple machines:

   

Machines
Physics
Quatr.us home