A boat is rowed at 8 km/hr directly across a river that flows at 6 km/hr. What is the resultant speed?

Sagot :

8 km/h +6km/h =14 km/h assuming that the boat is going the same direction as the current. 

The Resultant Speed of boat rowed at 8km/hr directly across a river that flows at 6km/hr is 10km/hr

Given the data in the question;

Velocity of boat; [tex]V_m = 8km/hr[/tex]

Velocity of the flowing river; [tex]V_r = 6km/hr[/tex]

Resultant Velocity; [tex]V = ?[/tex]

Now, as illustrated in the diagram below, a right angled triangle is formed.

Now, to get the V, which is the resultant velocity or speed, we make use of the Pythagorean theorem:

[tex]c^2 = a^2 + b^2[/tex]

In our case,

[tex]V^2 = V_r^2 + V_m^2[/tex]  

We find the square root of both sides

[tex]V = \sqrt{V_r^2 + V_m^2}[/tex]

 

Now, we substitute in our given values

[tex]V = \sqrt{(6km/hr)^2 + (8km/hr)^2}\\\\V = \sqrt{ (36km^2/hr^2) + ( 64 km^2/hr^2)\\[/tex]

[tex]V = \sqrt{100 km^2/hr^2[/tex]

[tex]V = 10km/hr[/tex]

Therefore, The Resultant Speed of boat rowed at 8km/hr directly across a river that flows at 6km/hr is 10km/hr

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