The nose of an ultra-light plane is pointed is pointed South and its airspeed indicator shows 35m/s. The plane is in a 10m/s wind blowing towards the SouthWest relative to the ground. What is the plane's speed with respect to ground?

Respuesta :

Answer:

[tex]v=42.66\ m.s^{-1}[/tex]

[tex]\beta=6.75^{\circ}[/tex] clockwise from the south.

Explanation:

Given:

  • velocity of the plane southwards, [tex]v_p=35\ m.s^{-1}[/tex]
  • velocity of the wind in south-west, [tex]v_w=10\ m.s^{-1}[/tex]
  • ∴Angle between the plane and wind velocities, [tex]\theta=45^{\circ}[/tex]

According to the vector addition rule, magnitude of the resultant velocity is given as:

[tex]v=\sqrt{v_p^2+v_w^2+2\times v_p.v_w\ cos\ \theta}[/tex]

[tex]v=\sqrt{35^2+10^2+2\times 35\times 10\ cos\ \45}[/tex]

[tex]v=42.66\ m.s^{-1}[/tex] is the plane's speed with respect to ground.

Direction of this resultant with respect to south:

[tex]tan\ \beta=\frac{v_w\ sin\theta}{(v_p+v_p\ cos\theta)}[/tex]

[tex]tan\ \beta=\frac{10\ sin\ 45}{(35+35\ cos\ 45)}[/tex]

[tex]\beta=6.75^{\circ}[/tex] clockwise from the south.

Answer:

The plane's velocity is [tex](v_{x},v_{y})=(-7.07,-42.07)[/tex].

Explanation:

Given that,

Airspeed v= 35 m/s

Speed of wind v'= 10 m/s

Let x be the east and y be the north.

We need to calculate the velocity along the x -direction

Using velocity component

[tex]v_{x}=-v'\cos\theta[/tex]

Put the value into the formula

[tex]v_{x}=-10\cos45[/tex]

[tex]v_{x}=-7.07\ m/s[/tex]

We need to calculate the velocity along the y -direction

Using velocity component

[tex]v_{y}=-(v'\sin\theta+v)[/tex]

Put the value into the formula

[tex]v_{y}=-(10\sin45+35)[/tex]

[tex]v_{y}= -42.07\ m/s[/tex]

Hence, The plane's velocity is [tex](v_{x},v_{y})=(-7.07,-42.07)[/tex].