Consider a plane with a velocity relative to the air of 195 m/s in a westerly direction. If the wind has a speed relative to the ground of 53 m/s (in an easterly direction), how long does it take for the plane to travel from one city to another that is due west of the first by 276 km?
Air speed=195 m/s (westerly)
Air velocity = 195 m/s (West=positive)
wind speed = 53 m/s (easterly)
wind velocity = -53 m/s
Ground velocity
= air velocity + wind velocity
= 195-53
= 142 m/s
Distance = +276 km = +276000 m
Time required
= Distance/velocity
= 276000/142 s
= 1944 s (approx.)
= 32.4 min. (approx.)