1) A 1.4-kg hawk, traveling west at 15 m/s, seizes a 0.20-kg dove. Just before b

Question

1) A 1.4-kg hawk, traveling west at 15 m/s, seizes a 0.20-kg dove. Just before being seized, the dove was flying east. Just after catching the dove, the hawk's speed is 12 m/s, and it is still moving west. What was the speed of the dove just before it was seized? Note: be careful with signs.

The dove's speed was _____ m/s (enter a positive value).

2) A 100 kg passenger enters a 1600 kg elevator, which carries him 120 m upward. If the elevator's power rating is 25 Kw (Kilowatts), what is the minimum amount of time (in seconds) required for ride?

The minimum time is ---------------- s

Explanation / Answer

1) conservation of momentum

1.4*15 - 0.2*v = (1.4 + 0.2)*12

v=9 m/s

2)

P = E/t = m g h/t

t = m gh/P = 1700*9.81*120/25.0E3= 80 s

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