Question

A relation of distance with time is given as d = 25(1-exp(-0.021t)) µm where d is in microns and t in seconds. What is the relation if d is in inches and t in minutes?

(a) 25(1-exp(-0.021t)) in

(b) 1.64(1-exp(0.26t)) in

(c) 3.84(1-exp(0.26t)) in

(d) 9.84(1-exp(1.26t)) in

The question was posed to me in an interview.

Question is taken from Dimensional Consistency in section Introductory Concepts of Chemical Process Calculation

Answer 1

The correct choice is (d) 9.84(1-exp(1.26t)) in

Explanation: Each term in an equation must have same dimensions and units as every other term to which it is added or subtracted or equated.