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# Relative Velocity Help

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1. (Original post by oShahpo)
Why is your Vbw = 3? The 3 is boat's velocity alone, not in relation to the water.
2. (Original post by RDKGames)
Why is your Vbw = 3? The 3 is boat's velocity alone, not in relation to the water.
That's not correct. Imagine if the water is so fast, going at say 1000 miles an hour, do you think the actual speed of the boat is going to be 3? Of course not, the boat will be blazingly fast relative to the harbour because the water is carrying the boat with it.
V boat = V boat relative to water + V water => makes sense as the actual velocity of the boat relative to the harbour is dependent upon both the speed of the water and that of the boat relative to the water.
Another way to think about it is this:
If you're on the surface of the Earth, on a bike going at 5 mph. Someone in outer space will see you moving at a much faster speed than 5 mph, because this 5 mph is your speed relative to the earth, but the speed the alien observes is your speed relative to earth + the speed of the earth.
3. (Original post by oShahpo)
That's not correct. Imagine if the water is so fast, going at say 1000 miles an hour, do you think the actual speed of the boat is going to be 3? Of course not, the boat will be blazingly fast relative to the harbour because the water is carrying the boat with it.V boat = V boat relative to water + V water => makes sense as the actual velocity of the boat relative to the harbour is dependent upon both the speed of the water and that of the boat relative to the water.Another way to think about it is this:If you're on the surface of the Earth, on a bike going at 5 mph. Someone in outer space will see you moving at a much faster speed than 5 mph, because this 5 mph is your speed relative to the earth, but the speed the alien observes is your speed relative to earth + the speed of the earth.
Makes sense, the wording of the question caught me out. Been a while since I've done relative velocity so I'm not completely convinced.

(Original post by tangotangopapa2)
Thank you so much. Really appreciate it.
Any way to verify the answer? Like an answer sheet or something?
4. (Original post by RDKGames)
Makes sense, the wording of the question caught me out. Been a while since I've done relative velocity so I'm not completely convinced.

Any way to verify the answer? Like an answer sheet or something?
That is the answer mentioned at the back (answer section) of the text book.

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