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#time period

3 public questions tagged with this topic.

A transverse wave on a string has a speed of 30 m/s and a wavelength of 1.5 m. What is the time period of the wave?

**Displacement relation** encodes λ = 2π/k and f = ω/2π. Comparing given equation y = a sin(kx - ωt) with standard form yields k and ω, hence λ = 2π/k and v = ω/k, essential for identifying propagation characteristics and phase. Speed: v = v λ , v = (v/λ) = (30/1.5) = 20 Hz . Time period: T = (1/v) = (1/20) = 0.05 s . Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields 0.05 s, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Wave Equation and Displacement Relation

A satellite near Earth has a period of 90 minutes. What is its period at h\=3RE? (RE\=6.4×106m)

T2∝(RE+h)3. T02 = kRE3, h = 3RE, r = 4RE. T2 = k(4RE)3 = 64kRE3. T = T064 = 90×8 = 720min. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 720 min. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.