SSC MTS · Bite-size lessons

Time, Speed and Distance

About 7 min · Numerical and Mathematical Ability · English

Time worked out from the lesson's 482 words at 150 words a minute, plus a minute for each question.

This topic tests your ability to connect three fundamental quantities: the distance traveled, the speed of movement, and the time taken. While the basic relationship is straightforward, SSC MTS questions add layers of complexity through scenarios involving trains crossing platforms, boats moving in rivers with currents, and problems involving relative motion between two objects.

Key ideas

• The fundamental relationship: Distance = Speed × Time. Any problem in this topic is a manipulation of these three variables. If two are given, the third can always be found.
• Unit consistency is non-negotiable: Speed in km/h with time in hours gives distance in km. Speed in m/s with time in seconds gives distance in meters. The most common error is mixing units without conversion.
• Conversion between km/h and m/s: To convert km/h to m/s, multiply by 5/18. To convert m/s to km/h, multiply by 18/5. Memorize this — it appears in nearly every train problem.
• Relative speed depends on direction: When two objects move in the same direction, relative speed = difference of speeds. When moving toward each other (opposite directions), relative speed = sum of speeds.
• Boats and streams introduce effective speeds: A boat's speed in still water is its own speed. Downstream speed = boat speed + stream speed. Upstream speed = boat speed − stream speed. The stream helps downstream, opposes upstream.

Watch out for

• Mixing units without conversion → Always convert km/h to m/s (or vice versa) before plugging into formulas. For train problems with lengths in meters and time in seconds, use m/s. For distances in km and time in hours, use km/h.
• Using arithmetic mean for average speed → The average of 40 km/h and 60 km/h is not 50 km/h when equal distances are traveled. Always use the harmonic mean formula for equal-distance scenarios.
• Forgetting to add lengths in train problems → When a train crosses a platform, the distance covered equals train length + platform length, not just the platform. When two trains cross, add both train lengths.

Quick reference

• Distance = Speed × Time; always maintain unit consistency.
• Convert km/h ↔ m/s: multiply by 5/18 or 18/5 respectively.
• Relative speed: add for opposite directions, subtract for same direction.
• Downstream = boat + stream; Upstream = boat − stream.
• Train crossing pole: distance = train length; platform: train + platform length.

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 21 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.

Read the full noteFlashcards for this topic