Question

two people are in a boat that is capable of a maximum speed of 5 kilometers per hour in still water, and wish to cross a river 1 kilometer wide to a point directly across from their starting point. if the speed of the water in the river is 5 kilometers per hour, how much time is required for the crossing?

Answer 1

The boat will not move across the river due to the equal and opposite speeds of the boat in still water and the river current.

To calculate the time required for the crossing, we need to calculate the velocity of the boat with respect to the ground. Since the boat is traveling across the river, we need to consider the effect of the river current on the boat's velocity. In this case, the boat is capable of a maximum speed of 5 km/h in still water, and the river current is also flowing at a speed of 5 km/h.

To find the boat's velocity with respect to the ground, we can use the concept of vector addition. The boat's velocity with respect to the ground is the vector sum of its velocity in still water and the velocity of the river current.

The velocity of the boat in still water is 5 km/h, and the velocity of the river current is 5 km/h in the opposite direction. When we add these vectors together, we get a resultant velocity of 0 km/h. This means that the boat will not make any progress across the river and will remain in the same position.

Therefore, no time is required for the crossing as the boat will not move across the river.

Learn more about river crossing