Relative Velocity The velocity of an object is relative to the observer who is making the measurement.
Ex. 11 - The engine of a boat drives it across a river that is 1800 m wide. The velocity vBW of the boat relative to the water is 4.0 m/s, directed perpendicular to the current. The velocity vWS of the water relative to the shore is 2.0 m/s. (a) What is the velocity vBS of the boat relative to the shore? (b) How long does it take for the boat to cross the river?
Ex. 12 - Two cars approach an intersection along perpendicular roads with the following velocities: vAG = velocity of car A relative to the ground = 25.0 m/s, eastward vBG = velocity of car B relative to the ground = 15.8 m/s, northward Find vAB, where: vAB = velocity of car A as measured by a passenger in car B.