A sound wave has a frequency of 5 kHz and wave length 50 cm. How long (in seconds) will it take to travel 5 km?
एक ध्वनि (sound) तरंग (wave) की आवृत्ति (frequency) 5 kHz और तरंगदैर्ध्य 50 से.मी. है। 5 कि.मी. की दूरी तय करने में इसे कितना समय (सेकंड में) लगेगा?
Answer और ExplanationAnswer and explanation
Answer: (A) 2
ध्वनि (sound) तरंग (wave) की चाल (speed) = आवृत्ति (frequency) × तरंगदैर्ध्य। आवृत्ति = 5 kHz = 5000 Hz, तरंगदैर्ध्य (wavelength) = 50 cm = 0.5 m। अतः चाल = 5000 × 0.5 = 2500 m/s = 2.5 km/s। दूरी (distance) = 5 km, समय = दूरी/चाल = 5/2.5 = 2 सेकं ड। इसलिए सही उत्तर 2 सेकंड है।
Speed of sound wave = frequency × wavelength. Frequency = 5 kHz = 5000 Hz, wavelength = 50 cm = 0.5 m. So speed = 5000 × 0.5 = 2500 m/s = 2.5 km/s. Distance = 5 km, time = distance/speed = 5/2.5 = 2 seconds. Thus the correct answer is 2 seconds.
Source: SSC MTS 2025 · 11 Feb 2026 · Shift 2। Solution: Prashant Sir, Sarvagya।Source: SSC MTS 2025 · 11 Feb 2026 · Shift 2. Solution by Prashant Sir, from Sarvagya.