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September 23rd, 2007, 10:36 AM   #1
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i've been stuck on these problems FOREVER. please help

I've been stuck on these problems forever and i still can't get it.

1) A boat is cruising at a constant speed of 2.2 m/s when it is shifted into neutral. After coasting 12.0 m the engine is engaged again, and the boat resumes cruising at the reduced speed of 1.6 m/s. How long did it take for the boat to coast the 12.0 m?

2) Landing with a speed of 125 m/s, and traveling due south, a jet comes to rest in 8.00 102 m. Assuming the jet slows with constant acceleration, find the magnitude and direction of its acceleration.

3) A bicyclist is finishing his repair of a flat tire when a friend rides by at 3.0 m/s. Two seconds later, the bicyclist hops on his bike and accelerates at 2.2 m/s2 until he catches his friend.

any help would be really appreciated
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October 27th, 2007, 07:03 AM   #2
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1. You'd need some extra information relating to the boat's speed when coasting.

2. What does "in 8.00 102 m" mean?

3. I understand the description, but what is the question?
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October 27th, 2007, 07:42 AM   #3
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Quote:
Originally Posted by skipjack
1. You'd need some extra information relating to the boat's speed when coasting.

2. What does "in 8.00 102 m" mean?

3. I understand the description, but what is the question?
For 1, I think you should assume constant deceleration from 2.2 m/s to 1.6 m/s.

For 2, it means that the jet decelerates at a constant rate from 125 m/s to 0 m/s in a distance of 8.00102 meters.

For 3, I suspect the question asks for either distance traveled or time required. Assume that the "hopping" takes 0 seconds.
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