Question

Two roads cross at right angles. An observer stands on the road 50 meters south of the intersection and watches an eastbound car traveling at 45 meters per second. What is the observer's speed relative to the car?

A. 0m/s
B. 45m/s
C. 50m/s
D. 63.64m/s

Answer 1

The observer's relative speed to the car moving east at 45 m/s is also 45 m/s since the observer is stationary relative to the east-west direction.

Therefore, the answer is B. 45m/s.

Step-by-step explanation:

When considering the observer's speed relative to the car, we need to analyze the motion from the perspective of the observer. The car is moving east at 45 meters per second, and since the roads cross at right angles, the observer to the south is not moving in the east-west direction.

The relative speed of the observer to the car in the direction of car's motion is therefore the same as the car's speed, which is 45 m/s. So, the observer's relative speed to the eastbound car is 45 m/s.

To find the observer's speed relative to the car, we need to consider their velocities. The observer is standing still, so their velocity is 0 m/s. The car is traveling east at 45 m/s. Since the observer is watching the car from a stationary position, their speed relative to the car is equal to the car's speed, which is 45 m/s.