Question by Cynthia Gomez: PHYSICS HELP WANTED ASAP?
solar sails—large sheets of material that would work by reflecting photons. Since the momentum of the photon would be reversed, an impulse would be exerted on it by the solar sail, and—by Newton’s Third Law—an impulse would also be exerted on the sail, providing a force. In space near the Earth, about 3.84 x10^21 photons are incident per square meter per second. On average, the momentum of each photon is 1.30 x 10^-27 kg m/s. For a 1325-kg spaceship starting from rest and attached to a square sail 24 m wide. What is the speed of ship in 1s.
The answer from back of book says 4.333 x 10^ -6 but I keep getting 4.92 x 10^ -6. ANYHELP !!!!
Best answer:
Answer by billrussell42
24 m square is 576 m²
take 1 second.
576 m² x 3.84e21 photons /m² = 2212e21 photons
2212e21 photons x 1.3e-27 kg m/s / photon = 2875e-6 kg m/s = 2.875e-3 kg m/s momentum change
But that is if the photons are absorbed. If they are reflected, the change is twice that
2 x 2.875e-3 kg m/s / 1325-kg = 4.34e-6 m/s
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