Concepts Of Physics MCQ Edition [Volume 1]PhysicsPhysics and Mathematics
A rod of length L is positioned along the X-axis between x = 0 and x = L . The linear density (mass/length) of the rod varies with the distance x from the origin as = a + bx . Determine the SI units of a and b .
Options
- Akg/m , kg/m ^2
- Bkg/m ^2 , kg/m
- Ckg/m , kg
- Dkg , kg/m
Correct answer
A. kg/m , kg/m ^2
Step-by-step solution
The linear density is defined as mass per unit length, so its SI unit is kg/m . According to the principle of dimensional homogeneity, each term in the equation = a + bx must have the same unit. Therefore, the unit of a is the same as the unit of , which is kg/m . Similarly, the unit of the term bx must be kg/m . Since x represents distance, its SI unit is m . Unit of b = Unit of Unit of x = kg/m m = kg/m ^2 . Thus, the SI units of a and b are kg/m and kg/m ^2 respectively.