When you use a spoon to open a lid from a tin, you are utilizing a simple machine called a lever. In fact, levers are the basis of lots of tools in and around your house and work. The way levers operate is by an effort applied at a point that moves a load at another point through a balance point called a fulcrum. It is the relative positions of these three points; the effort, the load and the fulcrum, which distinguishes the type or class of lever. For your information, there are three classes of lever 1st, 2nd and 3rd class. Well, here we are going to talk about all classes of levers, as well as examples of 1st, 2nd and 3rd Class Levers.
First Class Lever
You have to know that the first class lever has the fulcrum between the force and the load. In using a screwdriver to lift a lid from a tin, you are moving the effort over a greater distance than the load. By having the fulcrum (the rim of a tin) close to the lid (the load), a larger force will be able to be applied to the load to open the tin. Thus, it means that you are reducing the effort required. That is what first class levers do best. Other examples of first-class levers are scissors, pliers, a crow bar, a see-saw, a claw hammer, and a weighing balance.
In summary, we are able to say that in a first class lever the effort (force) will move over a large distance to move the load a smaller distance. And, in a first-class lever, the fulcrum is between the effort (force) and the load. When the ratio of effort (force) arm length to load arm length increases, then the mechanical advantage of a first-class lever increases. Archimedes referred to a first-class lever in his popular quote “Give me one firm spot on which to rest (a fulcrum) and I will move the Earth”.
Second Class Lever
Need to know that the second-class lever has the load between the effort and the fulcrum. A common example is a wheelbarrow where the effort will move a large distance to lift a heavy load, with the axle and wheel as the fulcrum. In a second-class lever, the effort will move over a large distance to raise the load a small distance. When the ratio of effort (force) arm length to load arm length increases, then the mechanical advantage of a second-class lever increases. In a wheelbarrow, the closer the load is to the wheel, then the greater the mechanical advantage. Also, nutcracker is an example of a second-class lever.
Third Class Lever
Third class lever has the effort (force) between the load and the fulcrum. A common example is in barbecue tongs. Other examples of third-class levers are a fishing rod, a broom, and a woomera. In a third-class lever, the load will move further than the effort (force). And, the mechanical advantage is low, which is why it is difficult to apply great force to the load. This is able to be an advantage by not squashing sausages on the barbecue. When you lift a load by using your forearm, then you are using a third-class lever. Your biceps muscles are attached to the forearm in front of the elbow. The load is on the hand. While, the effort is between the fulcrum (elbow) and the load.
Examples of 1st, 2nd, And 3d Class Levers
As we know that levers are the most basic machines that are used to do some work with minimal effort. A lever strengthens an input force to give a greater output force, which is said to give leverage. According to the position of the load and the work on the fulcrum, apparently there are three types or classes of levers.
Examples of First Class Lever
First Class Lever is a type of lever that has the fulcrum in between the weight and the force applied. Its order is represented as force-fulcrum-weight. First Class Lever is the most basic type of lever.
Here are some examples of first Class Lever:
- Our hand pushing an object or crowbars, seesaws.
- Using scissors represents the usage of two first-class levers.
- A wheel and axle are also an example.
- Pulling a nail out of a wooden plank represents a first-class lever.
Examples of Second Class Lever
In this second Class Lever, the fulcrum is at one end and the force applied is on the other end. The weight is in the middle of these two. The order of this one would be fulcrum-weight-force. The application of force at one end results in several work done on the other end.
Here are some examples of second Class Lever:
- Wheelbarrow
- Staplers
- Doors or gates
- Bottle openers
- Nutcracker
- Nail clippers
Examples of Third Class Lever
In this third Class Lever, the fulcrum is at one end and the force is applied in the middle and the weight is on the other end. The order of this one is represented as a weight-force-fulcrum. In this case, we must apply more energy to displace the weight to a longer distance.
Here are some examples of third Class Lever:
- Fishing rod
- A broom
- A baseball bats
- A bow and arrow
- Human jaw
- A hammer
Question
In the table below, which of the following are correct examples of 1st, 2nd and 3rd Class levers?
| First class Lever | Second class Lever | Third class Lever | |
| I | Scissors | Wheel barrow | Broom |
| II | Ice Tongs | Tweezer | Paper cutter |
| III | Pliers | Nut cracker | Fishing rod |
- I and II only
- II and III only
- I and III only
- I, II and III
Correct answer is C (I and III only)
Explanation:
First class lever has the fulcrum between the effort and the load. In a tweezer and ice tong, effort is between the fulcrum and the load. Thus, they are third class levers. In scissors and pliers, fulcrum is between the effort and the load. Thus, they are first class levers.
Second class lever has the load between the effort (force) and the fulcrum. In paper cutter, wheel barrow, and nut cracker, the load is between the effort and the fulcrum. So, they are second class levers.
Third class lever has the effort between the fulcrum and the load. A fishing rod and broom have the effort between the fulcrum and the load. Thus, they are third class levers.
Hence, in the table above, I and III are the correct examples of first, second and third-class levers.
