Physics
posted by Elaine Jetton .
A rowboat crosses a river with a velocity of 3.42 mi/h at an angle 62.5° north of west relative to the water. The river is 0.805 mi wide and carries an eastward current of 1.25 mi/h. How far upstream is the boat when it reaches the opposite shore?

north speed = 3.42 sin 62.5 = 3.03
time = .805/3.03 = .265 hours
west speed = 3.42 cos 62.5  1.25
= .329 mi/hr
distance west = .329*.265 = .0872 miles
By the way to cross a river fast, forget where you end up downstream and row or swim directly across in direction, not trying to get the right component upstream to end up across from where you started. This is important if swimming and tired. Do not fight the current.
Respond to this Question
Similar Questions

physic
Hi!Question: A river flows due east at 1.70m/s.A boat crosses the river from the south shore to the north shore by maintaining a constant velocity of 8.0m/s due north relative to the water. A.What is the velocity of the boat relative … 
PhysicsMechaincs
A rowboat crosses a river with a velocity of 1.01 m/s at an angle 30◦ North of West relative to the water. Water’s frame of reference: speed of boat: 1.01 m/s direction from current: 30◦ The river is 322mwide and carries … 
physic
A rowboat crosses a river with a velocity of 3.42 mi/h at an angle 62.5° north of west relative to the water. The river is 0.610 mi wide and carries an eastward current of 1.25 mi/h. How far upstream is the boat when it reaches the … 
physics
A rowboat crosses a river with a velocity of 4.23 mi/h at an angle 62.5o north of west relative to the water. The river is 0.543 mi wide and carries an eastward current of 0.73 mi/h. How far upstream is the boat when it reaches the … 
physics
A rowboat crosses a river with a velocity of 3.55 mi/h at an angle 62.5o north of west relative to the water. The river is 0.850 mi wide and carries an eastward current of 0.57 mi/h. How far upstream is the boat when it reaches the … 
Physics
A river flows due east at 1.42 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant velocity of 11.9 m/s due north relative to the water. If the river is 389 m wide, how far downstream is … 
Physics
A rowboat crosses a river with a velocity of 3.30 mi/h at an angle 62.5° north of west relative to the water. The river is 0.795 mi wide and carries an eastward current of 1.25 mi/h. How far upstream is the boat when it reaches the … 
physics
a river flows due east at 1.50 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant velocity of 10m/s due north relative to the water. (a) what is the velocity of the boat relative to the … 
Physics
A rowboat crosses a river with a velocity of 3.37 mi/h at an angle 62.5° north of west relative to the water. The river is 0.590 mi wide and carries an eastward current of 1.25 mi/h. How far upstream is the boat when it reaches the … 
Physics
A rowboat crosses a river with a velocity of 3.37 mi/h at an angle 62.5° north of west relative to the water. The river is 0.590 mi wide and carries an eastward current of 1.25 mi/h. How far upstream is the boat when it reaches the …