Question

Which is an example of levers class 3?
A. Scissors
B. Crowbar
C. Tweezers
D. Nutcracker

Answer 1

Hint: We will make use of the concept which says that in class three levers effort is between the fulcrum and resistance.

Complete step by step solution:
A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge or fulcrum. A lever is, therefore, a rigid body capable of rotating on a point on itself. On the basics of the locations of these fulcrums, load and effort, a lever is divided into three types. What a lever does is basically amplify an input force to provide a greater output force which is said to provide leverage. The ratio of the output force to the input force is referred to as mechanical advantage or otherwise commonly referred to as efficiency of the lever.
Levers are classified by the relative positions of the fulcrum, effort and resistance (or load). Commonly, the input force is called the effort and the output force the load or the resistance.
Thus, the example of class 3 levers is tweezers where the effort is between the fulcrum and the resistance.

Hence option C is the correct option.
While options A, B and D are incorrect because efforts are not between fulcrum and resistance.
Additional information:
There are three different types of levers:
Class 1: Here the fulcrum is between the effort and the resistance (or load). The effort is applied on one side of the fulcrum and load on the other.
Class 2: Load between the effort and the fulcrum.
Effort between the fulcrum and the resistance.

Note: Before solving the sum students need to be able to be able to distinguish between the different classes of levers based on the respective positions of the effort, load and the fulcrum.