A swimmer can swim at 3 km/h in still water. If he swims across a river flowing

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Question: A swimmer can swim at 3 km/h in still water. If he swims across a river flowing at 2 km/h, what is his resultant speed?

Options:

Correct Answer: 5 km/h

Solution:

Resultant speed = √(3² + 2²) = √(9 + 4) = √13 ≈ 3.6 km/h.

A swimmer can swim at 3 km/h in still water. If he swims across a river flowing at 2 km/h, what is his resultant speed?

A swimmer can swim at 3 km/h in still water. If he swims across a river flowing at 2 km/h, what is his resultant speed?

Step 1: Understand that the swimmer's speed in still water is 3 km/h.
Step 2: Recognize that the river is flowing at 2 km/h.
Step 3: Visualize the swimmer swimming across the river. His speed is at a right angle to the river's flow.
Step 4: Use the Pythagorean theorem to find the resultant speed. This is because the swimmer's speed and the river's speed form a right triangle.
Step 5: Calculate the square of the swimmer's speed: 3 km/h * 3 km/h = 9.
Step 6: Calculate the square of the river's speed: 2 km/h * 2 km/h = 4.
Step 7: Add the two results together: 9 + 4 = 13.
Step 8: Take the square root of the sum to find the resultant speed: √13.
Step 9: Calculate the square root of 13, which is approximately 3.6 km/h.

Relative Velocity – Understanding how to calculate the resultant speed of an object moving in a medium with a current.
Pythagorean Theorem – Applying the theorem to find the resultant speed when two velocities are perpendicular.