Relative Velocity problem

samedi 31 mai 2014

A flat rectangular barge,48m long and 20m wide, is headed directly across a stream at 4.5 km/h. The stream flows at 3.8 km/h. What is the Velocity, relative to the riverbed, of a person walking diagonally across the barge at 5km/h while facing the opposite upstream bank?



Hi Guys, having some trouble with this one would really appreciate some help.



Attempted solution-



Split the figures into three vectors being-



a (3.8,0)

b (0,4.5)

c 5v/|v| relative to the barge, where v=(48,20)

= sqrt 48^2 + 20^2= sqrt 2704= 52

=52/(48,20)

= (48/52,20/52)

= (12/13,5/13)

= 5 (12/13,5/13)

=(60/13,25/13)



(3.8+60/13,4.5 + 25/13)

=(8.4,6.4)



^ and thats as far as i have got





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