Question

What principle is used in a Newton spring balance?
A. The mass of an object depends on its density
B. The mass of an object depends on the gravity pulling
C. The weight of an object is directly proportional to its mass
D. The extension of the spring is directly proportional to the force pulling it.

Answer 1

Hint: A Newton spring balance works on the principle of Hooke's law. In order to know the answer, we need to consider the instrument that is, a Newton spring balance to know its components and their workings. The main component of this balance is the spring, as the extension of the spring is used to measure the weight of the object hung to the hook of the spring. This extension is measured in terms of force experienced by the spring.

Complete answer:
A Newton spring balance is a type of weighing machine/scale and is commonly used to measure the force exerted on the object/body. This force is measured in terms of the unit named Newton.
The object/material whose weight is to be measured will be hung to the spring connection of the Newton spring balance. The change in the length of the spring, that is, the extension of the spring is measured by a pointer in terms of force experienced by the spring in Newton unit.
In other words, we can say that the measure of the value of the pointer is equal to the force applied by the spring to pull the material/object attached to the hook of the balance.
The principle used in a Newton spring balance is that the extension of the spring is directly proportional to the force pulling it.

Thus, the option (D) is correct.

Note:
The principle of Hooke's law is used in the working of a Newton spring balance. Concerning the elastic limit of a material, the Hooke's law is defined as the strain of a material is proportional to the externally applied stress.