Question

Which one of the following is a scalar quantity?
A. Momentum
B. Electric charge
C. Shearing force
D. Displacement

Answer 1

In physics, we talk mainly about two types of quantities: a vector quantity and a scalar quantity. A scalar quantity is one which does not have any direction but only a magnitude. A vector quantity is one which has both direction as well as a magnitude.

Complete step-by-step answer:
We need to understand what are scalar and vector quantities.
Some physical quantities can be completely described by just their magnitude. Such quantities are known as scalar quantities. These quantities can be added or subtracted from each other by simple rules of algebra. For example: mass of a body, speed of a body, etc.
But there are certain physical quantities which cannot be described by just their magnitude but also require some knowledge of their direction to get their complete knowledge. Such quantities are known as vectors. For example: velocity of a body, acceleration of a body, etc.
1. Momentum: The momentum of a body can be defined as the product of the mass of a body and its velocity. It is a vector quantity because it possesses direction as well as magnitude.
2. Electric charge: It is a fundamental property of a material which causes a body to respond to an external electric or magnetic field. It does not possess any direction but only magnitude. So, it is a scalar quantity.
3. Shearing force: It is a type of force which pushes the different parts of a body in different directions. It is a vector quantity as it has a certain direction along which it acts.
4. Displacement: The displacement of a body is defined as the amount by which a body’s position has changed from the initial position and the direction in which it has changed its position. Since, we need to specify both magnitude and direction in case of displacement, the displacement is considered as a vector quantity.
Hence, the correct answer is option B.

So, the correct answer is “Option B”.

Note: A property which can be used to differentiate vectors and scalars is that the vector quantities cannot be added to each other through simple algebra but require a separate vector algebra to study their behaviour. The scalar quantities can be added using simple algebra.