question_answer

What is the difference between the following two data : (i) 8 (5 km/hr, east) (ii) (8 hr) (5 km/hr, east)?

Answer:

                (i) It is the product of a pure number and a vector (velocity), hence the unit of product is the same as that of vector i.e., the product is a velocity of 40 km/hr, towards east. (ii) It is the product of a scalar (time) and a vector (velocity). Hence the unit of the product will be hr \[\times \] (km/hr). Thus the product is a displacement of magnitude 40 km, towards east.