(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 hosepipe tends to go backward.
(b) Explain why, when a fireman directs a powerful stream of water on a fire from a hose pipe, the hosepipe tends to go backward.
(a) Newton's third law says that "For every action, there is an equal and opposite reaction". This can be understood by the two following examples:
(i) When we throw a ball to hit a wall in front of us, the ball comes back in our hands. This happens because, ball exerts a force on the wall but the wall exerts an equal and opposite force on the ball too, which brings the ball back in our hands.
(ii) Another example can be taken from walking of us on the ground. When we walk on the ground, we push the ground back by our feet, the ground applies an equal and opposite force in return that helps us to move forward.
(b) Newton's third law is applicable here. According to Newton's third law, for every action, there is an equal and opposite reaction. So, when the fireman directs the powerful stream of water, which is an action force, the hosepipe receives an equal and opposite reaction force. That's why hosepipe tends to move in a backward direction.
(a) Newton's third law says that "For every action, there is an equal and opposite reaction". This can be understood by the two following examples:
(i) When we throw a ball to hit a wall in front of us, the ball comes back in our hands. This happens because, ball exerts a force on the wall but the wall exerts an equal and opposite force on the ball too, which brings the ball back in our hands.
(ii) Another example can be taken from walking of us on the ground. When we walk on the ground, we push the ground back by our feet, the ground applies an equal and opposite force in return that helps us to move forward.
(b) Newton's third law is applicable here. According to Newton's third law, for every action, there is an equal and opposite reaction. So, when the fireman directs the powerful stream of water, which is an action force, the hosepipe receives an equal and opposite reaction force. That's why hosepipe tends to move in a backward direction.
