Question

A river current has a velocity of 5 km/h relative to the shore, and a boat moves in the same direction as the current at 5 km/h relative to the river. How can the velocity of the boat relative to the shore be calculated?
a.by subtracting the river current vector from the boat’s velocity vector
b.by dividing the river current vector by the boat’s velocity vector
c.by multiplying the vectors
d.by adding the vectors

Answer 1

Answer:

D. By adding the vectors

$V = 10km/h$

Explanation:

Given

Represent the velocity of the river current as VR

$V_R = 5km/h$

Represent the velocity of the boat as VB

$V_B = 5km/h$

Required

How to calculate the velocity of boat relative to river current

From the question, we understand that both move in the same direction.

So, the relative velocity V is calculated as:

$V = V_R + V_B$

$V = 5km/h + 5km/h$

$V = 10km/h$

Notice that the both velocities are added together to get the relative velocities.

This is so because they both move in the same direction

From the list of given options, only option D is correct.