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mikeportnoy February 16th, 2010 08:30 AM

relative velocities
 
An airplane A which can fly at a maximum speed of 800 km/h is going to overtake airplane B. Airplane B is flying to the east with a speed of 500km/h. Initially, B is at a position 100km and on a bearing of 240 degree from A.

(1) Find the minimum speed required of A to overtake B.

(2) If A flies at a speed of 400 km/h, find two possible directions of A so that A will be able to overtake B.


So I know I will have to start with a diagram, with A flying perpendicular to B for the minimum speed for (1)? Not sure bout (2).

skipjack February 18th, 2010 02:08 PM

The maximum speed of A is irrelevant in this question. The word "overtake" isn't clear when A and B are flying in different directions, so I am not sure what the question means by "overtake B". If A flies in a constant direction at the lowest speed that allows it to intercept B, it would be more reasonable to say that B overtakes A at the time of interception than that A overtakes B, and the same is true if A flies at 400 km/h. You should perhaps assume that "overtake" is to be interpreted as "intercept".


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