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## Homework Statement

The solar sail uses “radiation pressure” caused by the momentum of photons of sunlight as they strike the sail. A sail with an area of [itex]1.5 \times 10^6 m^2[/itex] could be used to propel a spacecraft of mass [itex]1.2 \times 10^3 kg[/itex].

The energy [itex]E[/itex] and momentum [itex]p[/itex] of a photon are related by the expression [itex]E = pc[/itex], where [itex]c[/itex] is the speed of light.

Calculate the total momentum of the photons striking [itex]1 m^2[/itex] of sail in one second. Assume the solar radiation flux (intensity) is [itex]1400 W m^{-2}[/itex].

## Homework Equations

[itex]p=mv[/itex]?

## The Attempt at a Solution

Can I have hint's on how to approach this.

The momentum eqaution that I know is [itex]p=mv[/itex] but I don't think I can use this.