Practice Questions
Concept Explanation
Convert between km/h and m/s before mixing units in one calculation.
Key Formulas
- km/h to m/s: multiply by 5/18
- m/s to km/h: multiply by 18/5
- 1 km/h = 5/18 m/s; 1 m/s = 18/5 km/h = 3.6 km/h
- 1 hour = 60 minutes; 1 minute = 60 seconds
Example
72 km/h = 72 × 5/18 = 20 m/s.
Common Trap
Do not use 5/18 when converting m/s to km/h. That factor applies only km/h → m/s.
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Q1 EasyConvert a speed of 72 km/h into metres per second. What is the equivalent speed in m/s?Explanation72 × 5/18 = 20 m/s.
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Q2 EasyA body moves at 15 m/s. What is its speed in km/h?Explanation15 × 18/5 = 54 km/h.
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Q3 EasyExpress 36 km/h in metres per second. What is the result?Explanation36 × 5/18 = 10 m/s.
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Q4 EasyWhat is 54 km/h when converted to metres per second?Explanation54 × 5/18 = 15 m/s.
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Q5 EasyConvert 10 m/s into km/h. What is the equivalent speed?Explanation10 × 18/5 = 36 km/h.
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Q6 EasyConvert 18 km/h to metres per second. What is the speed in m/s?Explanation18 × 5/18 = 5 m/s.
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Q7 EasyExpress a speed of 8 m/s in km/h. What is the equivalent value?Explanation8 × 18/5 = 28.8 km/h.
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Q8 EasyWhich of the following unit conversions is correct?ExplanationTo convert km/h to m/s, multiply by 5/18.
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Q9 MediumA vehicle travels at 25 m/s. What is its speed in km/h?Explanation25 × 18/5 = 90 km/h.
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Q10 MediumA car moves at 108 km/h. What is its speed in m/s?Explanation108 × 5/18 = 30 m/s.
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Q11 MediumWhat is 90 km/h expressed in metres per second?Explanation90 × 5/18 = 25 m/s.
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Q12 MediumAn object covers 1 km in exactly 1 minute. What is its speed in km/h?Explanation1 km per minute = 60 km/h.
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Q13 MediumA cyclist moves at 45 km/h. What is this speed in m/s?Explanation45 × 5/18 = 12.5 m/s.
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Q14 HardA runner covers 500 m in 25 seconds. What is the speed of the runner in km/h?Explanation500 ÷ 25 = 20 m/s, which equals 72 km/h.
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DS1 Easy
What is the speed of the object in m/s?
Statement IThe speed of the object is 72 km/h.
Statement IIThe object covers a distance of 20 m every second.
ExplanationEach statement alone gives 20 m/s (72 × 5/18, or directly 20 m/s). -
DS2 Easy
What is the speed of the object in km/h?
Statement IThe object covers 500 m in 25 seconds.
Statement IIThe speed of the object is 20 m/s.
ExplanationEach statement alone gives 20 m/s, which equals 72 km/h.
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DS3 Medium
What is the speed of the object in km/h?
Statement IThe speed of the object is 15 m/s.
Statement IIThe object covers 720 km in 4 hours.
ExplanationStatement I alone: 15 × 18/5 = 54 km/h. Statement II alone gives 180 km/h. -
DS4 Medium
Is the speed of the object greater than 20 m/s?
Statement IThe speed of the object is 90 km/h.
Statement IIThe speed of the object is 75 km/h.
ExplanationStatement I: 90 × 5/18 = 25 m/s > 20. Statement II: 75 × 5/18 ≈ 20.83 m/s > 20. Each alone is sufficient.