Answer
The total force resisting the motion of the boat is 2700 N.
Work Step by Step
We can convert the power to units of W:
$P=(35 ~hp)(\frac{746 ~W}{1 ~hp})=26,100 ~W$
Next, we find the average force exerted by the motor as it travels 35 km in 1 hour.
$\frac{F\cdot d}{t}=P$
$F=\frac{P\cdot t}{d}=\frac{(26,100 W)(3600 s)}{35,000 m}$
$F=2700 ~N$
Since the boat moves at a steady speed, the total force resisting the motion of the boat must also be equal (in magnitude) to 2700 N.
