Question

A balloon lifting in air follows:

• A. Law of gravitation
• B. Archimedes principle
• C. Laws of motion
• D. all of the above

Answer 1

The correct option is D all of the above

In a lifting balloon, force of gravitation acts downwards as on all other materials present on the earth, given by $mg$.

Also Archimedes' principle acts on the balloon to provide a buoyant force $V\rho g$ upwards, and greater in magnitude than the gravitational force downwards. (Where $\rho$ is the density of air)

Hence Newton's law of motion provides the acceleration of the balloon upwards, given by: $ma=V\rho g-mg$