A rowboat crosses a river with a velocity of 3.58 mi/h at an angle 62.5° north of west relative to the water.
Favorites|Homepage
Subscriptions | sitemap
HOME > Physics > A rowboat crosses a river with a velocity of 3.58 mi/h at an angle 62.5° north of west relative to the water.

A rowboat crosses a river with a velocity of 3.58 mi/h at an angle 62.5° north of west relative to the water.

[From: ] [author: ] [Date: 11-09-11] [Hit: ]
25 mi/h. How far upstream is the boat when it reaches the opposite shore?-we first find the time it takes the boat to cross the river; for this we need the component of motion of the boat across the river,the component of motion to the north is 3.58 sin 62.5 = 3.......
A rowboat crosses a river with a velocity of 3.58 mi/h at an angle 62.5° north of west relative to the water. The river is 0.870 mi wide and carries an eastward current of 1.25 mi/h. How far upstream is the boat when it reaches the opposite shore?

-
we first find the time it takes the boat to cross the river; for this we need the component of motion of the boat across the river, or in the northern direction

the component of motion to the north is 3.58 sin 62.5 = 3.18mi/hr

therefore it takes t=0.87mi/3.18mi/hr = 0.27h to cross the river

the total eastward component of motion is

-3.58 cos 62.5 + 1.25 = -0.4 mi/hr

meaning the boat is moving against the current

in the 0.27 h it takes to cross the river, the boat will be -0.4mi/h*0.27h = -0.1 mi upstream

the minus sign indicates upstream

-
I don't remember the cos tan sin thing but the velocity doesn't seem relevant. I believe you can use sine law though (side angle side) that's all I can remember though.
1
keywords: the,velocity,crosses,with,3.58,water,north,mi,of,to,west,at,62.5,deg,rowboat,angle,an,river,relative,A rowboat crosses a river with a velocity of 3.58 mi/h at an angle 62.5° north of west relative to the water.
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .