Physics MCQs for NEET — Practice Questions with Answers

The NCERT text mentions, 'Using, the kinetic theory of gases, the bulk measurable properties like viscosity, heat conductivity and diffusion can be related to the microscopic parameters like molecular size. It is through such relations that the molecular sizes were first estimated.' This highlights the role of kinetic theory, and particularly concepts like mean free path, in connecting the macroscopic and microscopic worlds.

According to the NCERT text, 'A scalar quantity is a quantity with magnitude only. It is specified completely by a single number, along with the proper unit. Examples are: the distance between two points, mass of an object, the temperature of a body and the time at which a certain event happened.' Acceleration, velocity, and displacement are vector quantities as they have both magnitude and direction.

The NCERT text states, 'W e found that the directional aspect of these quantities can be taken care of by + and – signs, as in one dimension only two directions are possible.' Unit vectors are used for motion in two or three dimensions.

The NCERT text highlights, 'But in order to describe motion of an object in two dimensions (a plane) or three dimensions (space), we need to use vectors to describe the above-mentioned physical quantities. Therefore, it is first necessary to learn the language of vectors.'

As per the NCERT text, 'The rules for combining scalars are the rules of ordinary algebra. Scalars can be added, subtracted, multiplied and divided'.

The NCERT states, 'A unit vector is a vector of unit magnitude and points in a particular direction. It has no dimension and unit. It is used to specify a direction only.'

As per the NCERT, 'Multiplying a vector A with a positive number $\lambda$ gives a vector whose magnitude is changed by the factor $\lambda$ but the direction is the same as that of A : $|\lambda A| = \lambda |A|$ if $\lambda > 0$.'

The NCERT text explains, 'Multiplying a vector A by a negative number $-\lambda$ gives another vector whose direction is opposite to the direction of A and whose magnitude is $\lambda$ times $|A|$'.

The summary explicitly states, 'Scalar quantities are quantities with magnitudes only. Examples are distance, speed, mass and temperature.' It further states, 'Vector quantities are quantities with magnitude and direction both. Examples are displacement, velocity and acceleration.'

The text mentions, 'These unit vectors are perpendicular to each other.'