Q17 of 124 Page 74

To take the boat away from the bank of a river, the boatman pushes the bank with an oar. Why?

Pushing of the river bank is an action, the river thus pushes back the boat in the forward direction as a reaction in accordance with the Newton's third law of motion which states that every action has a equal and opposite reaction.


More from this chapter

All 124 →
15

Fill in the following blanks with suitable words:

(a) To every action, there is an ………. and ……..reaction.


(b) Momentum is a ……..quantity. Its unit is …………….


(c) Newton’s second law of motion can be written as Force = mass × …………… or Force = …………….. or change of …………


(d) Forces in a Newton’s third law pair have equal …………… but act in opposite …………


(e) In collisions and explosions, the total ………… remains constant, provided that no external ………… acts.

 16

Explain the meaning of the following equation:

F = m × a


Where symbols have their usual meaning.

 18

Why does a gunman get a jerk on firing a bullet?

 19

If action is always equal to reaction, explain why a cart pulled by a horse can be moved.