Question

All of the following situations can be explained using Newton's $3rd$ Law, except for one of them.
Which situation can NOT be explained using $3rd$ Law ideas?

• A. An inflated balloon is not tied and is let go. It moves forward as it pushes air backward out of the hole
• B. The gravitational interaction between Earth and the Moon affects both objects, with Earth's tides mostly due to the Moon's gravitational pull
• C. A projectile's horizontal velocity remains constant because gravity is a vertical force and no horizontal force acts on the projectile
• D. A propeller airplane would not work in outer space because propellers work by pushing backward to more the airplane forward

Answer 1

The correct option is C A projectile's horizontal velocity remains constant because gravity is a vertical force and no horizontal force acts on the projectile

Newton's third law states that for every action force there is a reaction pair force.

Hence an inflated balloon moving forward pushes air backward out of the hole and its reaction pair pushes balloon forward. A propeller airplane works the same way.

Gravitational force of earth on moon has a reaction pair where moon exerts force on earth. Hence the force on water on earth creates tides.