An observer on the ground sees an eagle flying towards thep east at 15m/s chasing a hummingbird flying at 5 m/s. He approximates that the mass of the eagle is 4 times that of the hummingbird. If the eagle catches the hummingbird and continues to fly with the same thrust from its wings, what speed with the observer see them moving at?
Correct answer: B. 13m/s
- A. 10m/s
- B. 13m/s
- C. 16m/s
- D. 7m/s
Explanation
Let mass of hummingbird=m1. Mass of eagle = m2 =4m1 By law of conservation of momentum;M1v1 + m2 v2 = (m1+m2)x5m1 + 15(4m1) = (m1 +4m1)x65m1 = 5m1 xX = 13
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