Question

Question 38:
(a) State Newton’s third law of motion and give two examples to illustrate the law.
(b) Explain why, when a fireman directs a powerful stream of water on a fire from a hose pipe, the hose pipe tends to go backward.


Lakhmir Singh Physics Class 9

Answer 1

Answer:

a) for every action, there is an equal and opposite reaction if f1 is acting and F2 is reacting then by definition F1 = -F2

here (-)sign is used to show opposite direction

Answer 2

Answer:

Explanation:

(a) Newton’s third law of motion states that whenever a body exerts a force on another body, the second body exerts equal and opposite force on the first body.

Examples - When a person jumps out from a boat, the boat moves backward. This is because to step out of the boat, the person presses the boat with their foot in a backward direction. The push on the boat in action and the boat exerts an equal force in the forward direction. Since, the boat is not fixed and is floating, it moves backward due to the action force exerted.

(b) When a fireman directs a powerful stream of water on a fire, the hose pipe tends to go backward due to the water's reaction force rushing through it in the forward direction with great speed.