Verified Solution • 2025–26 Session moderate

Q1.5: NCERT Physics - Part 1 UNITS AND MEASUREMENT 1.5 Solution: A new unit of length is chosen such that the speed of light in…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students frequently fail to convert the mixed time unit (minutes and seconds) into a single base unit (seconds) before applying the formula, leading to incorrect multiplication. Always convert the entire duration to seconds ($8 \times 60 + 20 = 500$ s) to ensure consistency with the speed defined as 1 unit per second.

A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance?

Step-by-Step Verified Solution

**Answer:** 500 new units. **Step-by-Step Explanation:** Time taken = 8 min 20 s = 8×60+20=5008 \times 60 + 20 = 500 s. Since speed of light = 1 new unit/s:
d=c×t=1×500=500 new unitsd = c \times t = 1 \times 500 = 500 \text{ new units}

All Questions in this Chapter

Q1.1 Q1.2 Q1.3 Q1.4 Q1.5 Q1.6 Q1.7 Q1.8 Q1.9 Q1.10 Q1.11 Q1.12 Q1.13 Q1.14 Q1.15 Q1.16 Q1.17

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