COMEDK2023Evening ShiftPhysicsUnits and DimensionsActual
The time dependence of a physical quantity P is give by P=P ₀ (- t^2 ) where is a constant and t is time. The constant will
Options
- AHave no dimensions
- BHave dimensions as that of P
- CHave dimensions equal to that of Pt ^2
- DHave dimensions of t⁻²
Correct answer
D. Have dimensions of t⁻²
Step-by-step solution
The given equation is P = P₀ (- t^2) . In any exponential function of the form e^x , the exponent x must be dimensionless. Therefore, the term t^2 must be dimensionless. [ t^2] = [M^0 L^0 T^0] = 1 . Since t represents time, its dimension is [T] . Thus, [ ] [T^2] = 1 . [ ] = [T⁻²] . This implies that the constant has dimensions of t⁻² . Answer: Have dimensions of t⁻²