Question
Download Solution PDFLight with an energy flux of 500 kW/m2 falls for 5 minutes at normal incidence on a non-reflecting circular surface with a radius of 10 cm. The total momentum delivered to this surface has a magnitude of ______.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
Time = 5 minutes = 300 s
Radius (r) of a circular surface = 10 cm = 10 × 10−2 = 10−1 m
Energy Flux, S = 500 kW/m² = 500 × 103 W/m²
Concept:
The energy per unit area per unit time passing through a plane perpendicular to the wave is called the energy flux, denoted by S.
- S = E / (t × A) = E / (πr²t)
- E = S × πr² × t
- Momentum, p = E / c
Explanation:
- E = S × πr² × t = 500 × 103 × 300 × π × (10−1)²
- E = 15π × 105 J
Momentum, p = E / c
- p = (15π × 105) / (3 × 108) = 5π × 10−3 kg·m·s−1
Hence, the correct answer is p = 5π × 10−3 kg·m·s−1
Last updated on May 26, 2025
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