The route followed by a hiker consists of three displacement vectors, X, Y and Z. Vector X is along a measured trail and is 1430m in a direction 42 degrees north of east. Vector Y is along a measured trail that goes 2200m due south. The hiker then follows vector Z and ends up back where they started, so that X + Y + Z = 0. Find the magnitude of Z and an angle that specifies its direction.

Respuesta :

Answer:

  • magnitude : 1635.43 m
  • Angle: 130°28'20'' north of east

Explanation:

First, we will find the Cartesian Representation of the [tex]\vec{X}[/tex] and [tex]\vec{Y}[/tex] vectors. We can do this, using the formula

[tex]\vec{A}= | \vec{A} | \ ( \ cos(\theta) \ , \ sin (\theta) \ )[/tex]

where [tex]| \vec{A} |[/tex] its the magnitude of the vector and θ the angle. For  [tex]\vec{X}[/tex] we have:

[tex]\vec{X}= 1430 m \ ( \ cos( 42 \°) \ , \ sin (42 \°) \ )[/tex]

[tex]\vec{X}= ( \ 1062.70 m \ , \ 956.86 m \ )[/tex]

where the unit vector [tex]\hat{i}[/tex] points east, and [tex]\hat{j}[/tex] points north. Now, the [tex]\vec{Y}[/tex] will be:

[tex]\vec{Y}= - 2200 m \hat{j} = ( \ 0 \ , \ - 2200 m \ )[/tex]

Now, taking the sum:

[tex]\vec{X} + \vec{Y} + \vec{Z} = 0[/tex]

This is

[tex]\vec{Z} = - \vec{X} - \vec{Y}[/tex]

[tex](Z_x , Z_y) = - ( \ 1062.70 m \ , \ 956.86 m \ ) - ( \ 0 \ , \ - 2200 m \ )[/tex]

[tex](Z_x , Z_y) = ( \ - 1062.70 m \ ,  \ 2200 m \ - \ 956.86 m \ )[/tex]

[tex](Z_x , Z_y) = ( \ - 1062.70 m \ ,  \ 1243.14 m\ )[/tex]

Now, for the magnitude, we just have to take its length:

[tex]|\vec{Z}| = \sqrt{Z_x^2 + Z_y^2}[/tex]

[tex]|\vec{Z}| = \sqrt{(- 1062.70 m)^2 + (1243.14 m)^2}[/tex]

[tex]|\vec{Z}| = 1635.43 m[/tex]

For its angle, as the vector lays in the second quadrant, we can use:

[tex]\theta = 180\° - arctan(\frac{1243.14 m}{ - 1062.70 m})  [/tex]

[tex]\theta = 180\° - arctan( -1.1720)  [/tex]

[tex]\theta = 180\° - 45\°31'40'' [/tex]

[tex]\theta = 130\°28'20''  [/tex]