Respuesta :
To find the displacement of the plane during the third leg (as a vector), multiply the velocity of the plane times the time that it travels at that velocity:
[tex]\Delta\vec{r_3}=\vec{v}_3t[/tex]The velocity of the plane with respect to the ground v_PG is equal to the velocity of the plane with respect to the wind v_PW, plus the velocity of the wind with respect to the ground v_WG:
[tex]\vec{v_{}}_{PG}=\vec{v}_{PW}+\vec{v}_{WG}[/tex]The direction of the wind is θ=280°, and its speed is 35mph:
[tex]\begin{gathered} \vec{v}_{WG}=(35\text{mph}\cdot\cos (280),35\text{mph}\cdot\sin (280)) \\ =(6.078\text{mph,}-34.47\text{mph)} \end{gathered}[/tex]The direction of the plane with respect to the wind is θ=70, and the magnitude of its velocity is the same as in the 2nd leg, which is 560mph. Then:
[tex]\begin{gathered} \vec{v}_{PW}=(560\text{mph}\cdot\cos (70),560\text{mph}\cdot\sin (70)) \\ =(191.5\text{mph,}526.2\text{mph)} \end{gathered}[/tex]Add both velocities to find the velocity of the plane with respect to the ground:
[tex]\begin{gathered} \vec{v}_{PG}=(6.078mph,-34.47mph)+(191.5mph,526.2mph) \\ =(6.078mph+191.5mph,-34.47mph+526.2mph) \\ =(197.6mph,491.9mph) \end{gathered}[/tex]Since 20 minutes is 1/3 of an hour, then the displacement during the third leg of the trip, is:
[tex]\begin{gathered} \Delta\vec{r}_3=\frac{1h}{3}(197.6mph,491.9mph) \\ =(65.9\text{miles,}164\text{miles)} \end{gathered}[/tex]1st question:
To find the position of the plane from the origin, add the displacement vector to the position before the 3rd leg started, which is:
[tex]\vec{r_2}=(576.5miles,359.15miles)[/tex]Then, the final position after the third leg, is:
[tex]\begin{gathered} \vec{r_{}}=\vec{r}+\Delta\vec{r} \\ =(576.5miles,359.15miles)+(65.9\text{miles,}164\text{miles)} \\ =(576.5miles+65.9\text{miles,}359.15miles+164\text{miles)} \\ =(642\text{miles,}523\text{miles)} \end{gathered}[/tex]Then, the final location of the plane, is:
[tex]\vec{r}=(642\text{miles,}523\text{miles)}[/tex]2nd question:
To find how far from the take-off point the plane is, calculate the magnitude of the vector r:
[tex]\begin{gathered} |\vec{r}|=\sqrt[]{r_x+r_y} \\ =\sqrt[]{(642mi)^2+(523mi)^2} \\ =828\text{miles} \end{gathered}[/tex]Therefore, the plane is 828 miles away from the take-off point.
3rd question:
To find the direction of the plane (the angle θ), remember that:
[tex]\begin{gathered} \tan \theta=\frac{r_y}{r_x} \\ \Rightarrow\theta=\arctan (\frac{r_y}{r_x}) \\ =\arctan (\frac{523miles_{}}{642\text{miles}}) \\ =\arctan (\frac{523_{}}{642}) \\ =39^{\circ} \end{gathered}[/tex]Therefore, the direction of the plane is 39° from the East toward the North.
