The speed of the boat in still water is 18 km / h. The speed of the river is 2 km / h.

The speed of the boat in still water is 18 km / h. The speed of the river is 2 km / h. How long does it take for the boat to go 80 km along the river? against the stream?

The speed of movement of the vessel in still water is given, the speed of the river flow is given, and the distance that is required to travel is given.

The time that must be spent on passing the path is equal to the ratio of the distance and the speed of the vessel.

If the ship is moving along the course of the river, then the speed of the ship is equal to the sum of the speeds of the ship in still water and the speed of the course of the river itself. If the vessel is moving against the current, then the “+” sign is replaced by the “-” sign.

t (downstream) = S / (V + Vflow) l

t (downstream) = 80/20 = 4 hours.

t (upstream) = S / (V – Vflow) = 80/16 = 5 hours.