How Far Downstream Will the Swimmer End Up?

AI Thread Summary
The discussion focuses on calculating how far downstream a swimmer will end up when crossing a river with a current. The river current is 22 m/s south, and the swimmer's speed is 47 m/s at an angle of 7.5 degrees south of east. By combining the swimmer's and current's velocities, a resultant speed of 54.433 m/s at an angle of 31.122 degrees south of east is determined. Given the river's width of 325 meters, the swimmer is projected to end up 196 meters downstream upon reaching the opposite bank. The calculations are confirmed, though the poster invites others to verify the results.
thegame
Messages
32
Reaction score
0
river current = 22 m/s [South]
width of the river from one side to the other = 325m
speed of person swiming = 47 m/s



if the person travels 47 m/s [E 7.5 degrees S] then how far up or down the stream will he end up when he reaches the other side?
 
Physics news on Phys.org
alright! i just did a ton of these!

first, find the vector V(current)+V(swimmer)
if you draw it, you get a triange with one leg 47, another 22, and the angle between them 97.5

then solve for the hypotnuse (c^2=a^2+b^2-2ab cos C), which gives you the magnitude of 54.433

use the same equation to get the angle formed by the hypotnuse and the swimmer. this is 23.622 degrees.

since the swimmer is at a 7.5 degree angle, add this to 23.622,
31.122

now you draw the river. from one side to the other is 325 m. now draw a line [E 31.122 S] and use inverse tan to get the answer,
196 m down

someone may want to double check. i might have done something stupid, or even did it wrong all together. haha.
 
After trying it a few times, I got 196m too..
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
Back
Top