NCERT Solutions for Class 9 Science Chapter 11
Important NCERT Questions
Work and Energy
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Exercises Questions
Page No-159
Questions No-19
Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?
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1. Newton’s Second Law:
– Newton’s Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).
2. Forces in Equilibrium:
– When multiple forces act on an object simultaneously, their combined effect determines the object’s acceleration.
– If the forces are balanced or cancel each other out, resulting in a net force of zero, the object is in a state of equilibrium.
3. Zero Net Force, Zero Acceleration:
– In a state of equilibrium where the net force is zero, according to Newton’s Second Law, the acceleration of the object will be zero, regardless of the number of forces acting on it.
– Balanced forces prevent any change in the object’s motion, maintaining either rest or constant velocity (zero acceleration).
4. Examples of Equilibrium:
– An object at rest on a surface experiences forces like gravity pulling it downward and the normal force from the surface pushing upward. If these forces are equal in magnitude and opposite in direction, the object remains stationary with zero acceleration.
– Similarly, an object moving at a constant velocity experiences balanced forces, resulting in zero net force and zero acceleration despite multiple forces acting on it.
5. Conclusion:
– Zero acceleration is possible when the forces acting on an object are in equilibrium, canceling each other out and resulting in a net force of zero according to Newton’s Second Law.
Therefore, I concur with Soni that an object can have zero acceleration even when several forces are acting on it if these forces are balanced and create a state of equilibrium where the net force on the object is zero. This state prevents any change in the object’s motion, leading to zero acceleration.