A small boat moving at 15 km/h crosses a 350 m wide river. The water runs at 6 m/s towards the left. Calculate:

5.1 The resultant velocity of the boat.

First, we need to calculate the velocity of the boat relative to the water.

Since the boat is moving at 15 km/h and the water is running at 6 m/s towards the left, we need to convert the boat's velocity to m/s:

15 km/h = 15,000 m / 3600 s = 4.167 m/s

Therefore, the boat's velocity relative to the water is 4.167 m/s.

Next, we can calculate the resultant velocity of the boat by using the Pythagorean theorem:

Resultant velocity = sqrt((4.167)^2 + (6)^2)
Resultant velocity = sqrt(17.36 + 36) = sqrt(53.36) = 7.3 m/s

So, the resultant velocity of the boat is 7.3 m/s.