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Specialty Chemistry Forums => Other Sciences Question Forum => Topic started by: zeshkani_usa on January 19, 2013, 11:59:58 PM

Title: boat crossing
Post by: zeshkani_usa on January 19, 2013, 11:59:58 PM

to cross a river that is 1km wide, with a current of 6km/hr, a boat that is perpendicular to the far bank, the boat speed is 10km/hr. at what position will the boat actually contact the far bank? what direction should the boat have to cross directly across?

the first part i did this 10²+6²=11.6km/h is the diagonal speed

time=1/10= .1    distance = .1x 11.6 is the distance
and from here the acutal distance would be =squareroot1.16²-1²  which comes to be 0.58km

and the second part would it be the inverse tan of of 1/10 = 5.7degrees but to get the total degrees would it jsut be 180+5.7= 185.7 degress

does this seem right?

Title: Re: boat crossing
Post by: Borek on January 20, 2013, 06:12:20 AM

What do you need the diagonal speed for? Motions are independent, just calculate how long it takes to cross the river and then calculate how far the boat drifted during this time.