(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A battleship steams due east at 24 km/h. A submarine 4.0 km away fires a torpedo that has a speed of 50 km/h. If the ship is seen 20º east of north, in what direction should the torpedo be fired to hit the ship?

2. Relevant equations

x motion of ship: x = vt

x motion of torpedo: x' - x[itex]_{}0[/itex]' = v[itex]_{}x[/itex]'t

y motion of torpedo: y - y[itex]_{}0[/itex] = v[itex]_{}y[/itex]t

3. The attempt at a solution

The torpedo will hit the ship when its at y = 0, thus solve for t in the y motion equation of the torpedo.

0 - y[itex]_{}0[/itex] = v[itex]_{}y[/itex]t

Then x = x'

In which you get x[itex]_{}0[/itex] + v[itex]_{}x[/itex] (-y[itex]_{}0[/itex] / v[itex]_{}y[/itex]) = x[itex]_{}0[/itex]' + v[itex]_{}x[/itex]' (-y[itex]_{}0[/itex] / v[itex]_{}y[/itex])

Do some algebra and you get x[itex]_{}0[/itex] - x[itex]_{}0[/itex]' = (v[itex]_{}x[/itex]' - v[itex]_{}x[/itex]) / v[itex]_{}y[/itex]

But I can't solve for [itex]\Theta[/itex]

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# Homework Help: Having trouble with relative motion

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