Question

A river flows at 2m/s. The velocity of a ferry relative to the shore is 4m /s at right angle to the current. What is the velocity of the ferry relative to the current?

Answer 1

The velocity of the ferry relative to the current is 4.5 m/s.

Relative velocity

• Relative velocity is the velocity of a body as observed from the reference point of another body either stationary or in motion.

Since the river is flowing parallel to the shore and the ferry is moving perpendicular to the shore, their velocities are at right angles to each other.

The two velocities form a right angled-triangle of sides 2, 4 and a hypotenuse which gives the relative velocity of the ferry to the current.

Using Pythagoras rule:

• c² = a² + b²

• Let c be the hypotenuse
• a =  velocity of the ferry, and
• b = the velocity of the current, and

c² = 4² + 2²

c² = 16 + 4

c = 20

c = √20

c = 4.47 m/s

c ≈ 4.5 m/s

Therefore, the velocity of the ferry relative to the current is 4.5 m/s.

Learn more about relative velocity and Pythagoras rule at: brainly.com/question/25617868