Question

Which of the following is a third class lever?
A. Crowbar
B. Nutcracker
C. Scissors
D. Tongs

Answer 1

Hint: Learn about levers thoroughly and the different types of levers, basic differences between them.Levers are the most common devices that are used to perform tasks with the least amount of effort. Here we will discuss types of lever and see which of the options represents which type of lever.

Complete answer:
Leverage occurs when a lever amplifies an input force to produce a greater output force. We are aware that different types of levers exist, depending on the fulcrum location, force, and weight. Any method that is used to conduct work falls into one of these categories.

According to where the load and effort are located with respect to the fulcrum, there are three types or class of lever:
-First class Lever
-Second class Lever
-Third class Lever

First class Lever: The fulcrum of this type of lever is located between the weight and the force applied. The force-fulcrum-weight order is used to describe it. The most basic form of lever is this one.By looking at the options we can identify that crowbar and scissors are examples of first class levers.

Second class Lever: The fulcrum is at one end, while the force is applied at the other.The weight is in the centre of these two options. This will be in the following order:fulcrum-weight-force. The use of force at one end will result in any work being performed at the other.By looking at the options we can easily identify that nutcracker is the second class lever.

Third class Lever: The fulcrum is at one end of the lever, the force is applied in the centre, and the weight is at the other end. A weight-force-fulcrum is used to represent the class. In this case, we must expend more energy to move the weight over a greater distance.We can identify, by looking at the options, that tongs are the third class lever.

Therefore, option D is correct.

Note:One should focus on the fulcrum and load of a given lever in class to classify it into one of the three above mentioned types of levers. Remember that the mechanical advantage of a first class lever is greater than one, for second class it is less than one, and for third class lever it is equal to one.