# A plane flies at 250 km/h [N].  After flying for 2.0 h the plane has been blown off course 40 km [SW].  What is the resulting velocity of the plane?

jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted on

Initailly the velocity is 250Km/h to the North.

After blown off apart from the 250km/h to the North we have a velocity component of 40Km/h to south west.

So if we convert the SW velocity to components South and west we will get;

Velocity component to west   = 40*cos45

Velocity component to south = 40*sin45 ;same thing can be expressed as -40*sin45 to the north.

Now we can add up Velocity component to North.

Then resulting velocity to North = 250+(-40*sin45) km/h

= 221.716 km/h

Now we have two velocities;

first one to the North(221.716) and next to the west(40*sin45).

So the resultant velosity = sqrt(221.716+40*sin45)

=223.513 km/h

The direction of resultant force= tan-1(221.716/40*sin45)

= 82.73 degrees from west

Therefore the final velocity is 223.513 km/h to a direction 82.73 degrees from west.

Assumptions

• At the blown off still the plane remain its 250 km/h [N]

najm1947 | Elementary School Teacher | (Level 1) Valedictorian

Posted on

As I understood the problem, it is the distance of 40 Km SW to which the plane is blown off course from the point it would have reached after 2 hours i.e. 2x250 = 500 km due North.

In this situation the blown off position to from 500km N is

towards South = 40.cos(45) = 28.28km

towards West = 40.sin(45) = 28.28km

Resultant position = 500-28.28 = 471.72 N and 28.28 W

Resultant direction = tan-1(28.28/471.72) = 3.43 degree NW

Distance covered in 2 hours = sqrt(471.72^2+28.28^2) = 472.567km

Resultant velocity = 472.567/2 = 236.28km/h

The resultant velocity of the plane is 236.28 km/h in direction 3.43 degrees NW