Question

Which of the following situation(s) can be considered to be at rest for an observer travelling in a moving car?

• A. Birds flying at the same speed in the same direction as that of the moving car.
• B. Children crossing the road in front of the moving car.
• C. Trees planted on the sides of the road.
• D. A cat sleeping in the same car.

Answer 1

Answer: (A), (D)

The correct options are
A Birds flying at the same speed in the same direction as that of the moving car.
D A cat sleeping in the same car.

When an observer is travelling in his car, he will see those objects to be at rest which are moving with the same speed and in the same direction as that of the moving car. All the other objects would appear to be in motion.
Since the flying birds and sleeping cat have the same speed and direction as that of the observer in the moving car, they appear to be at rest to the observer.