A boat, whose speed in still water is 1.96 m/s, must cross a W = 217 m wide river and arrive at a point D = 111 m upstream from where it starts, as shown in figure below.
To do so, the pilot must head the boat at a 42.9° upstream angle. What is the speed of the river's current?
if u resolve the inital velocity
then u will get the vertical component to be 1.96*cos 42.9
= 0.732 * 1.96=1.434 m / s
time taken to cross = 217 / 1.434=151.32seconds
distance travelled in x direction = 111m
initial velocity in x direction = - 1.96 * sin 42.9 =
= -0.680 *1.96= - 1.33
disance = speed * time
d = (v of current + velocity of man) * time
111= (v - 1.33)* 151.32
v - 1.33 = 0.733
v= 1.33 + 0.73 = 2.063
