Question

Two physical quantities whose dimensions are not same, cannot be :

Answer 1

Answer:

displacement[L] , time[T] , and velocity[L/T] all three have different dimensions. ... This discussion on Two physical quantities whose dimensions are not same, cannot be :a)multiplied with each otherb)dividedc)added or substracted in the same expressiond)added togetherCorrect answer is option 'C'.

Answer 2

When dimensions are not same, two physical quantities can not be added or subtracted.

Explanation:

• The dimensions of a physical quantity are the  powers (or exponents) to which the base quantities are raised to represent that  quantity.

• The nature of a physical quantity is described  by its dimensions.
• All the physical quantities  represented by derived units can be expressed  in terms of some combination of seven  fundamental or base quantities.

• There is a basic set of dimensions from which we can define the dimension of all other  physically measurable quantities these include the most commonly used ones: Length (L), Mass (M), Time (T), Charge (Q).

• Only quantities with same dimensions can be added or subtracted.

Example for dimension : Speed = distance/time = $\frac{L}{T}=LT^{-1}$