The speed of the boat against the current of the river is 16.5 km / h, the speed of the river is 2.3 km / h.

The speed of the boat against the current of the river is 16.5 km / h, the speed of the river is 2.3 km / h. How far the boat will go in 3 hours, moving along the river.

Moving along the river, the boat receives acceleration through the river (the river pushes the boat), therefore vpo t. = Vsov. + vt. Knowing that when moving against the flow of the river, the boat slows down by the flow of the river and vth. t. = vcob. – vt, we get vcob. = vprot. t. + vt. Combining these formulas, we have vpo m. = Vt. + vprot. t. + vt.

Given:

vt = 2.3 km / h;

vprot. t = 16.5 km / h;

t = 3 h.

To find:

S by t. -?

Decision:

According to the formula vpo t. = Vt. + vprot. t. + vt. let’s calculate the speed of the boat going along the river:

1) 2.3 + 16.5 + 2.3 = 21.1 (km / h) – the speed of the river.

To find the path that the boat will pass in 3 hours downstream, you need to multiply the downstream speed by the time:

2) 21.1 * 3 = 63.3 (km) – the boat will pass in 3 hours, moving along the river.

Answer: 63.3 km.