An airplane maintains a speed of 645 km/h relative to the air it is flying through as it makes a trip to a city 724 km away to the north.(a) What time interval is required for the trip if the plane flies through a headwind blowing at 32.1 km/h toward the south?___________ h(b) What time interval is required if there is a tailwind with the same speed?_____________ h(c) What time interval is required if there is a crosswind blowing at 32.1 km/h to the east relative to the ground?_____________h

Respuesta :

Answer:

(a) 1.18 h

(b) 1.07 h

(c) 1.124 h

Solution:

As per the question:

Speed of the airplane, [tex]v_{a} = 645\ km/h[/tex]

Speed of the wind, [tex]v_{w} = 32.1\ km/h[/tex]  

Distance, d = 724 km

Now,

(a) To calculate time taken for the trip when the wind blows towards south:

The plane flies towards North and the wind blows towards South.

Thus the velocity of the airplane is given by:

[tex]v = v_{a} - v_{w} = 645 - 32.1 = 612.9\ km/h[/tex]

Thus the time taken, t = [tex]\frac{d}{v} = \frac{724}{612.9} = 1.18\ s[/tex]

t = 1.18 h

(b) To calculate the time interval in case of the tailwind:

Now, the direction of the wind and the plane is same:

Velocity of the plane, [tex]v' = v_{a} + v_{w} = 645 + 32.1 = 677.1\ km/h[/tex]

Time interval, t' = [tex]\frac{d}{v'} = \frac{724}{677.1} = 1.07\ h[/tex]

(c) To calculate the time interval in case of a crosswind:

[tex]v" = \sqrt{v_{a}^{2} - v_{w}^{2}}[/tex]

[tex]v" = \sqrt{645^{2} - 32.1^{2}} = 644.2\ km/h[/tex]

Time taken, t" = [tex]\frac{d}{v"} = \frac{724}{644.2} = 1.124\ h[/tex]