Benny is a student of class IX in a city school but his brother John studies in class V. One day John was playing with his friends just outside the house. John had a ballon in his hands. John inflated the ballon by filling air into it. He did not tie the mouth of this air-filled ballon with a thread. John just held the mouth of the inflated ballon tightly in the downward direction (towards the ground) and released it. When the inflated ballon (containing compressed air) was released with its mouth in the downward direction, then the ballon moved upwards on its own. Benny was observing this incident vert carefully. The upward going ballon reminded Benny of the principle of working of an important device. Benny also explained everything to his younger brother.
Name the device whose principle of working is demonstrated by the inflated ballon released by John?
(b) Name and state the principle (or law) on which the above device works.
(c) Explain and working of this device briefly.
(d) Which of the Newton's laws can also be said to be involved in the working of the above device?
(e) Name another device which also works on the same principle as this device.
(f) What values are displayed by Benny in this episode?

Explanation

(a) The upward moving ballon demonstrates the principle of working of a rocket.
(b) The rocket works on the principle of conservation of momentum or law of conservation of momentum. According to the law of conservation of momentum: When two (or more) bodies act upon one another, their total momentum remains constant (or conserved) provided no external forces are acting.
(c) The chemicals inside the rocket burn and produce high velocity blast of hot gases. These hot gases rush out through the tail nozzle of the rocket in the downward direction with tremendous speed or velocity. Although the mass of gases emitted is comparatively small, but they have a very high velocity and hence a very large momentum. An equal momentum is imparted to the rocket in the opposite direction, so that inspite of its large mass, the rocket goes up with a high velocity (to balance the momentum of downward going gases).
(d) Newton's third law of motion (which says: To every action there is an equal and opposite reaction).
(e) Jet aeroplanes also work on the same principle as a rocket.
(f) The values displayed by Benny in this episode are (i) Keen observation of happenings around him (ii) Knowledge of the working of rockets and jet aeroplanes, and (iii) Desire to impart knowledge to his younger brother.