Asked by kudu
A man who can swim at 5km/h in still water swims towards the east to cross arriver. If the river flows from north to south at the rate of 3km/h
a) Calculate:
i) The resultant speed
ii) The drift
b) If the width of the river is 30m, find the time taken, in seconds, for the man to cross the river
a) Calculate:
i) The resultant speed
ii) The drift
b) If the width of the river is 30m, find the time taken, in seconds, for the man to cross the river
Answers
Answered by
Henry
X = 5 km/h
Y = -3 km/h
i. Speed = Sqrt(X^2+Y^2) = sqrt(5^2+3^2)= 5.83 km/h = 1.62 m/s.
b. Tan A = Y/X = -3/5 = -0.60
A = -31o = 31o S. of E.
d = 30m/Cos(-31) = 35 m. = Distance to cross.
d = V*t = 35 m.
t = 35/V = 35/1.62 = 21.6 s.
Y = -3 km/h
i. Speed = Sqrt(X^2+Y^2) = sqrt(5^2+3^2)= 5.83 km/h = 1.62 m/s.
b. Tan A = Y/X = -3/5 = -0.60
A = -31o = 31o S. of E.
d = 30m/Cos(-31) = 35 m. = Distance to cross.
d = V*t = 35 m.
t = 35/V = 35/1.62 = 21.6 s.
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