Boats and streams applications – UGC NET Question

Statements A, B, C and D correctly describe standard boats and streams situations. A and B give the definitions of downstream and upstream speeds. C is true because if u − v = u + v, then v must be zero. D is correct since when the stream speed is non-zero, going against the current reduces effective speed and increases travel time for the same distance. E is false because if the stream is faster than the boat in still water, the boat cannot progress upstream relative to the ground. Therefore, A, B, C and D only are correct.

Option A:
Option A is incomplete as it omits C and D, both of which provide important consequences of the definitions, one algebraic and one about time comparisons in exam problems.

Option B:
Option B is also incomplete since it excludes D, missing the key implication that upstream travel takes longer when there is a current.

Option C:
Option C is wrong because it drops A and includes only B, C and D, leaving out the basic downstream speed definition that underlies the others.

Option D:
Option D is correct because it includes all the true statements and properly excludes E, which incorrectly permits upstream motion even when the current is stronger than the boat’s still-water speed.