When you think of a lever, you may think of a piece of construction machinery or laboratory equipment. But like most simple machines, levers are part of your everyday life — and in many ways, they make your everyday life possible!
Levers are the most basic machines which are used to do some work with minimal effort. A lever amplifies an input force to provide a greater output force, which is said to provide leverage.
We are aware that there are various types of levers depending on the position of the fulcrum, the force, and the weight. Every tool which is used to perform work comes under any one of these categories.
Keep reading for examples of levers that you see every day, including in the house, in the garden, and in the sports world.
What is a Lever?
A lever is a simple machine made of a rigid beam and a fulcrum. The effort (input force) and load (output force) are applied to either end of the beam. The fulcrum is the point on which the beam pivots.
When an effort is applied to one end of the lever, a load is applied at the other end of the lever. This will move a mass upward. Levers rely on torque for their operation. Torque is the amount of force required to cause an object to rotate around its axis (or pivot point).
A lever provides a mechanical advantage. Mechanical advantage refers to how much a simple machine multiplies an applied force. The location of the effort, load, and fulcrum will determine the type of lever and the amount of mechanical advantage the machine has.
The farther the effort is away from the fulcrum, the easier it is to move the load.
Examples Of First Class Lever
First-class levers have the fulcrum between the force and the load. In a first-class lever, the effort (force) moves over a large distance to move the load a smaller distance, and the fulcrum is between the effort (force) and the load. As the ratio of effort (force) arm length to load arm length increases the mechanical advantage of a first-class lever increases.
In using a screwdriver to lift the lid from a paint tin you are moving the effort over a greater distance than the load. By having the fulcrum (the rim of the tin) close to the lid (the load) a larger force can be applied to the load to open the tin. This means you are reducing the effort required, this is what first-class levers do best.
Other examples of first-class levers are pliers, scissors, a crowbar, a claw hammer, a seesaw, and a weighing balance.
Examples of levers in the first-class category include:
- Car jack – a car jack applies the force from your hand to push a car up. The fulcrum is between your hand and the car, making it a first-class lever.
- Claw end of a hammer – when you’re using a hammer to pull a nail out of wood, you’re using it as a first-class lever.
- Crowbar – like the claw end of a hammer, a crowbar’s fulcrum is between the effort (your hands) and the load (what you’re trying to pry).
- Gardening shears – the shears are joined in the middle (the fulcrum), and the force applied from your hands causes the other end to act upon the load (the shrub or tree that you’re pruning).
- Light switch – when you push down one side of the light switch, the effort carries over the fulcrum and the other side comes up.
- Pliers – the item you are gripping or twisting is the load, and the bolt in the middle is the fulcrum.
- Scissors – the blades of a set of scissors are joined in the middle (the fulcrum). When you act on one side, the action is performed on the other.
- Seesaw – a seesaw is the classic example of a first-class lever. It has a pivot point in the middle, the load on one side and the effort on the other.
Second Class Lever Examples
In second-class levers, the load is between the effort (force) and the fulcrum. A common example is a wheelbarrow where the effort moves a large distance to lift a heavy load, with the axle and wheel as the fulcrum.
In a second-class lever, the effort moves over a large distance to raise the load a small distance. As the ratio of effort (force) arm length to load arm length increases, the mechanical advantage of a second-class lever increases.
In a wheelbarrow, the closer the load is to the wheel, the greater the mechanical advantage. Nutcrackers are also an example of a second-class lever.
Examples of levers in the second-class category include:
- Bicycle Hand Brake – When you need to slow or stop your bike, you pull the hand brake. The force from your hand is transmitted through the lever and into the brake cables. (Some bike brakes, such as roller cam and U-brakes, are first-class levers.)
- Bottle Opener – A handheld bottle opener uses a straight beam balanced between your hand (the force) and the bottle cap (the load).
- Car Door Handle – When you lift the handle of a car door, it applies force to the hinge, which is on the other side of the beam.
- Crash Bar – When you leave a public building, you may find a crash bar instead of a door handle. Pushing down on the lever makes your effort to work on the door latch, which opens the door.
- Door – Opening a door is also a second-class lever function. It uses the hinge as a fulcrum to help the door swing open.
- Nail Clippers – Like all second-class levers, nail clippers have the effort and the fulcrum at opposite ends of the beam (the top clipper).
- Stapler – Just like nail clippers, the beam on the top of a stapler uses the force from your hand to place a staple into the paper (the load).
- Wheelbarrow – The load is in the middle of the wheelbarrow, you (the force) are moving it, and the wheel’s axle (the fulcrum) is on the other side.
Third Class Lever Examples
With third-class levers, the effort is between the load and the fulcrum, for example in barbecue tongs. Other examples of third-class levers are a broom, a fishing rod, and a woomera.
In a third-class lever, the load moves further than the effort (force) and the mechanical advantage is low, which is why it’s difficult to apply great force to the load. This can be an advantage by not squashing sausages on the barbecue!
When you lift a load using your forearm you are using a third-class lever. Your biceps muscles are attached to the forearm just in front of the elbow. The load is on the hand, and the effort is between the fulcrum (elbow) and the load.
Look at these examples of levers in the third-class category:
- Baseball bat – Look at a batter in slow motion. One hand holds the bat while forces from the entire body swing the bat with the other hand, working on the load (the ball).
- Broom – One hand grips the broom and the other applies force to sweep debris on the floor, which is the load.
- Chopsticks – The chopstick closest to your hand works as the fulcrum and the other chopstick (the beam) uses the force from your fingers to pick up food.
- Golf club – Just like a bat, a golf club functions as a third-class lever, using the force from one hand to swing.
- Hammer end of a hammer – When you’re hammering a nail into a board, you’re using a hammer at a third-class level. Your wrist is the fulcrum, and the load is the wood that you are driving the nail into.
- Rake – Similar to a broom, you use a rake by applying force from one hand and balancing it in the other (the fulcrum).
- Tennis racket – When you hit a tennis ball with one hand, your wrist acts as the fulcrum. When you hit it with two, your second hand is the fulcrum.
- Your arm – You’ve got two levers attached to your body! Any time you pick up an item, your elbow works as the fulcrum, your forearm is the beam, and your muscles carry the effort forward to work on what you’re picking up (the load).