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Calculate the joggers average velocity

  • #1
A canoeist wants to travel straight across a river that is 0.10 km wide. However, there is a strong current moving downstream with a velocity of 3.0km/h. The canoeist can maintain a velocity realitive to the water of 4.0km/h.
a) In what diretion should the canoeist head to arrive at a position on the other shore directly opposite to his starting position?
b) How Long will the trip take him?
AND
A jogger runs 15km(N 35 degrees E) and then runs 7.5 km (N 25 degrees W) It takes a total of 2.0 hours to run,
a)determine the displacement of the jogger
b)calculate the joggers average velocity
(I have to break this one into x and y components but I just cant seem to get it right).
 

Answers and Replies

  • #2
Office_Shredder
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For the canoist, call x the axis across the river, and y the axis going parallel to the river. What must be the y component of the canoe? How can you then solve for the x component?

For b, what are the standard trig formulae for x and y components?
 
  • #3
First one:
c²=a²+b²
4²=3²+b²
16-9=b²
b=2.65

Tan= opp/adj
tan=3/4
=o.75*tan-1
=37 degrees
answer is suppose to be 41

Second one:
x components:12.29+(-3.17)=9.12
y components=8.60+6.79=15.39
83.1744+236.8521=c²
320.0265=c²
c=18

answer is suppose to be 2.0*10¹ km(N 16 degrees east)
 

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