State with reasons, whether the following algebraic operations with scalar and vector physical quantities are meaningful :
$(a)$ adding any two scalars,
$(b)$ adding a scalar to a vector of the same dimensions ,
$(c)$ multiplying any vector by any scalar,
$(d)$ multiplying any two scalars,
$(e)$ adding any two vectors,
$(f)$ adding a component of a vector to the same vector.
$(a)$ Meaningful : The addition of two scalar quantities is meaningful only if they both represent the same physical quantity.
$(b)$ Not Meaningful : The addition of a vector quantity with a scalar quantity is not meaningful.
$(c)$ Meaningful : A scalar can be multiplied with a vector. For example, force is multiplied with time to give impulse.
$(d)$ Meaningful : A scalar, irrespective of the physical quantity it represents, can be multiplied with another scalar having the same or different dimensions.
$(e)$ Meaningful : The addition of two vector quantities is meaningful only if they both represent the same physical quantity.
$(f)$ Meaningful : A component of a vector can be added to the same vector as they both have the same dimensions.
Given vector $\overrightarrow A = 2\hat i + 3\hat j, $ the angle between $\overrightarrow A $and $y-$axis is
State, for each of the following physical quantities, if it is a scalar or a vector : volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency, displacement, angular velocity.
The unit vector parallel to the resultant of the vectors $\vec A = 4\hat i + 3\hat j + 6\hat k$ and $\vec B = - \hat i + 3\hat j - 8\hat k$ is
Surface area is
Define scalar and vector physical quantities with their examples.