This page covers SSC GD Constable Speed Distance Time with complete concept notes, 16 graded practice MCQs, key points and exam-specific tips. Free to study.
Core ConceptRead this first — the foundation of the topic
Speed, Distance, and Time form the foundation of motion problems in SSC CGL. This topic appears in 2-3 questions per exam and requires strong formula application skills. Core Concept: Speed measures how fast an object moves. Distance is the path covered. Time is the duration taken. These three are linked by a simple relationship that forms the base of all calculations.
Formula BlockMemorise — at least one formula appears in every paper
• Speed = Distance/Time (S = D/T)
• Distance = Speed × Time (D = S × T)
• Time = Distance/Speed (T = D/S)
Unit Conversions (Critical for SSC):
• km/hr to m/s: Multiply by 5/18
• m/s to km/hr: Multiply by 18/5
• 1 km/hr = 5/18 m/s
Exam PatternsWhat examiners ask — read before attempting PYQs
Shortcut 1 - Unit Conversion Trick
To convert km/hr to m/s, multiply by 5/18
Remember
36 km/hr = 10 m/s (this is a standard conversion to memorize)
Shortcut 2 - Distance Formula Rearrangement
When speed increases by x%, new time = Original time × 100/(100+x)
When speed decreases by x%, new time = Original time × 100/(100-x)
Worked ExampleSolve this step-by-step before moving on
Convert to m/s
Speed in m/s = 60 × 5/18 = 300/18 = 16.67 m/s
Answer: 16.67 m/s
Worked Example 2:
A train running at 54 km/hr takes 20 seconds to cross a platform 200m long. Find the length of the train.
1
Step 1
Convert speed to m/s
54 km/hr = 54 × 5/18 = 15 m/s
2
Step 2
Find total distance covered
Distance = Speed × Time = 15 × 20 = 300m
3
Step 3
Find train length
Train length = Total distance - Platform length = 300 - 200 = 100m
Answer: 100 meters
Shortcut 3 - Relative Speed:
• Same direction: Relative speed = |S1 - S2|
• Opposite direction: Relative speed = S1 + S2
Most Common Trap (#1 Mistake):
Students forget unit conversions! SSC deliberately mixes km/hr and m/s in the same question. Always check units in options and convert accordingly. Questions asking for train crossing times usually need m/s, while car journey problems often use km/hr.
Another frequent error is confusing relative motion directions. When two objects move toward each other, add their speeds. When moving in the same direction, subtract speeds.
Time-based problems often trick students with percentage changes in speed. Remember: if speed increases by 25%, time decreases by 20% (not 25%). Use the reciprocal relationship carefully.
Practice identifying whether the question asks for train length, crossing time, or platform length. Each requires different approaches but uses the same core formula.
Key Points to Remember
Master formula: Speed = Distance/Time and its variations D = S × T and T = D/S
Unit conversion: km/hr to m/s multiply by 5/18, m/s to km/hr multiply by 18/5
Standard conversion: 36 km/hr = 10 m/s (memorize this)
Relative speed: same direction subtract speeds, opposite direction add speeds
Train problems: Total distance = Train length + Platform/Bridge length
Speed increase by x%: New time = Original time × 100/(100+x)
Speed decrease by x%: New time = Original time × 100/(100-x)
Always check units in answer options before solving
Average speed = Total distance/Total time (not average of individual speeds)
Time and speed are inversely proportional when distance is constant
Exam-Specific Tips
1 km/hr equals exactly 5/18 m/s
36 km/hr equals exactly 10 m/s
72 km/hr equals exactly 20 m/s
Average speed formula: Total distance divided by total time
Relative speed when objects move toward each other: Sum of individual speeds
Relative speed when objects move in same direction: Difference of individual speeds
When speed increases by 20%, time decreases by 16.67%
When speed decreases by 20%, time increases by 25%
Practice MCQs
Speed Distance Time — Practice Questions
16graded MCQs · easy to hard · full solution & trap analysis
A cyclist covers 180 metres in 9 seconds. What is his speed in m/s?
Practice 2easy
A train travels at 72 km/h. How long will it take to cover 360 km?
Practice 3easy
A car travels 240 km in 4 hours. What is its average speed in km/h?
Practice 4easy
A bus travels 150 km in 2.5 hours. What is its speed in km/h?
Practice 5easy
A man walks at 5 km/h. How far will he walk in 3 hours?
Practice 6easy
A motorcycle covers 96 km in 1.5 hours. What is its speed in km/h?
Practice 7medium
Two cyclists start from the same point. Cyclist A travels at 15 km/h and Cyclist B travels at 12 km/h in the same direction. After how many hours will they be 9 km apart?
Practice 8medium
A train travels 360 km at a speed of 90 km/h. If the train had travelled 10 km/h faster, how many minutes less would it have taken?
Practice 9medium
A boat travels 48 km downstream in 3 hours and the same distance upstream in 4 hours. What is the speed of the boat in still water?
Practice 10medium
A person covers a certain distance at 40 km/h and returns via the same route at 60 km/h. If the total time taken is 5 hours, what is the total distance covered?
Practice 11hard
A car travels 120 km at a speed of 60 km/h, then 80 km at a speed of 40 km/h. What is the average speed (in km/h) for the entire journey?
Practice 12hard
Two cyclists start from the same point and travel in opposite directions on a circular track of 600 m. Cyclist A travels at 12 m/s and Cyclist B at 8 m/s. After how many seconds will they meet for the second time?
Practice 13hard
A train travels from Station A to Station B, covering 240 km in 4 hours. On the return journey, it travels at 80% of its original speed. If the train takes a 30-minute break at Station B before returning, what is the total time (in hours) taken for the entire round trip including the break?
Practice 14hard
Two trains start simultaneously from stations A and B, which are 450 km apart. Train X travels from A to B at 60 km/h, and Train Y travels from B to A at 90 km/h. At what distance from station A will they meet?
Practice 15hard
A runner covers a certain distance at 8 m/s and returns at 6 m/s. If the total time taken is 70 minutes, what is the total distance covered (in metres)?
Practice 16hard
A boat takes 6 hours to travel 120 km downstream and 8 hours to travel the same distance upstream. If the boat's speed in still water is B km/h and the current's speed is C km/h, what is B + C?
60-Second Revision — Speed Distance Time
Formula: Speed = Distance/Time, Distance = Speed × Time, Time = Distance/Speed
Remember: 36 km/hr = 10 m/s for quick conversions
Unit conversion: km/hr to m/s multiply by 5/18
Trap: Always check if answer needs km/hr or m/s units
Relative speed: Add for opposite directions, subtract for same direction