- #1
chaoseverlasting
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Homework Statement
A bird, 720 km away from a train flies towards it at a speed of 120km/h. As soon as it reaches the train, it turns back towards the wall (starting position). The train travels at a speed of 15m/s towards the starting position of the bird. How much distance towards the wall will the bird cover before the train reaches it.
The Attempt at a Solution
15m/s= 54km/h
Thus the train takes 720/54=13.33 hours to reach the wall.
The relative velocity of the bird wrt train when traveling towards it is 54+120=174km/h
The relative velocity when traveling away from the train is 120-54=66km/h
Ratios of velocities (towards:away)=29:11
Thus the ratio of time taken in traveling towards the train to away from the train =11:29
Thus, the bird spent a total of [tex]\frac{29}{29+11}\times 13.33[/tex] hours traveling away from the train.
The velocity of the bird traveling away from the train is 120km/h
Thus, the distance traveled by the bird away from the train is [tex]13.33\times \frac{29}{40} \times 120=1160 km[/tex]
Which is the wrong answer. The solution is 800 km. Why?