Physics Help Forum Forces and Motion - Relative Motion Question
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 Jul 6th 2009, 07:02 PM #1 Junior Member   Join Date: Jul 2009 Posts: 2 Forces and Motion - Relative Motion Question Amanda is walking her dog on an extendable leash. The leash can extend for 20m. If Amanda is walking at 4m/s [E] and the dog is walking at 1m/s [E] relative to Amanda. How far has the dog travelled from its original starting point by the time it reaches the end of the leash? Thank you for your help!
 Jul 7th 2009, 04:57 AM #2 Physics Team   Join Date: Feb 2009 Posts: 1,425 In future please attempt to answer at least, or post your specific difficulty. Amanda walks eastwards at 4 m/sec The dog walks east with respect to Amanda at 1 /sec. (Thus the vel of the dog is 5 m/sec east. ) Hence the leash will unravel at 1 m/sec till it reaches its limit of 20 m. At a vel of 1 m/sec, this will take 20 sec. The speed of the dog is 5 m /sec with respect to the ground. Thus in 20 secs, it will cover 20 x 5 = 100 m.

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