UGC NET Questions (Paper – 1)

A is correct since opposing motions add speeds, and B is correct as same-direction relative speed is the difference between speeds. C is true because when trains cross, they must cover the sum of their lengths relative to each other. E is also correct because the units are consistent so distance is directly in kilometres. D is false because distance is speed × time, not speed ÷ time. Hence the combination A, B, C and E only is correct.

Option A:
Option A leaves out E, failing to note the important unit consistency that allows direct interpretation of distance in kilometres. Though it includes true statements, it is not complete.

Option B:
Option B omits A and thus does not mention the case of opposite direction motion, which is central for many train problems. This makes the description insufficient.

Option C:
Option C is incomplete because it leaves out B, ignoring the same-direction relative speed rule, and so does not cover all key cases used in exam questions.

Option D:
Option D is correct, bringing together all true statements and excluding D, which misstates the basic speed–distance relation. It matches the conceptual framework required for time–speed–distance and train problems.

Statements A, B and C give core rules for relative speed questions. A is correct because approaching objects in opposite directions effectively close the distance at the combined speed. B is true since when moving in the same direction, the faster gains on the slower at the difference of their speeds. C is also correct because when trains cross each other completely, the total length to be covered relative to one another is the sum of their lengths. D is false because inconsistent units for speed and distance must be converted before using formulas, and E is false since on a circular track the time of meeting depends on relative speed, which involves differences for same-direction motion. Thus, A, B and C only are correct.

Option A:
Option A is incomplete as it lists only A and B and omits C, thereby failing to mention the specific structure of train-crossing problems where lengths are added.

Option B:
Option B is also incomplete since it includes only A and C and omits B, so it does not explicitly state how same-direction relative speed is computed.

Option C:
Option C is incomplete as it contains only B and C and omits A, losing the rule for opposite-direction motion.

Option D:
Option D is correct because it collects all three true statements about relative speeds and excludes D and E, which misrepresent unit conversion requirements and the nature of circular-track meetings.