Thursday, July 30, 2009

Vectors question?

a. a swimmer leaves point a swimming south across a river at 2 km/hr. the river is 4 km wide and flows east at the rate of 1 km/hr. make a vector diagram showing her resultant velocity.





b. calculate her resultant speed





c. how long will it take her to swim across the river? how far east does she swim?

Vectors question?
b)


her resultant speed in km/h is


sqrt(1^2+2^2)=sqrt(5)=2,24 (something near that)





c) She swims south at speed 2 km/h and the river is 4 km


wide (in N-S direction) so it takes 4/2=2 hours to reach the


other side


In that 2 hours the water of the river (with her in it) has flown


2 km east


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