As per Newton's first law of Motion

An object at Rest will continue to be at Rest

or

An object in Motion will continue to be in uniform motion in a straight line

unless

it is acted upon by an unbalanced force

 

In easy language

A stationary object will continue to be stationary

and

A moving object will continue to be moving in uniform motion

if there is no unbalanced force acting on it

 

Example 1

A pen kept on table will not move by itself

If we push it, then only it moves

This is because when we push it, we apply unbalanced force on it

Pushing Pen.gif

 

Example 2

If we throw a ball on ground,it stops after some time

This is due to force of friction which opposes motion of ball

This force of friction is more than force of ball (it is unbalanced force)

This unbalanced force make ball stop

Ball Stops.gif

 

Questions

NCERT Question 4 - A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, the ball comes to rest. The ball slows to a stop because

(a) the batsman did not hit the ball hard enough.

(b) velocity is proportional to the force exerted on the ball.

(c) there is a force on the ball opposing the motion.

(d) there is no unbalanced force on the ball, so the ball would want to come to rest.

View Answer

 

 

NCERT Question 10 - Using a horizontal force of 200 N, we intend to move a wooden cabinet across a floor at a constant velocity. What is the friction force that will be exerted on the cabinet? 

View Answer

 

  1. Class 9
  2. Chapter 9 Class 9 - Force and Laws Of Motion

About the Author

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CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 9 years and a teacher from the past 16 years. He teaches Spoken English, Written English, Grammar and Vocabulary at Englishtan.