Question

ncert class 9 science chapter 9 theory

correct answer = points
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Answer 1

Answer:

The rate of change of momentum of an object is directly proportional to the applied unbalanced force in the direction of the force.

Δptαm(v−u)t

⇒Δptαma

⇒Fαma

⇒F = kma

For 1 unit of force on 1 kg mass with the acceleration of 1m/s2, the value of k = 1.

Therefore, F = ma.

Answer 2

Introduction to Force

A force is an effort that changes the state of an object at rest or at motion. It can change an object’s direction and velocity. Force can also change the shape of an object.

Balanced and Unbalanced Forces

When balanced forces are applied to an object, there will be no net effective force acting on the object. Balanced forces do not cause a change in motion.

Unbalanced forces acting on an object change its speed and/or direction of motion. It moves in the direction of the force with the highest magnitude.