Balanced and Unbalanced Force

Resultant Force:

The measure of amount or strength of force is called the magnitude of force. many forces may be applied simultaneously on a body. For example

Several people can together can push a box. In this case each person pushes it that is applies some force on it. These forces together produce some acceleration in the box. It is also possible that one strong man pushes the box hard enough to produce the same acceleration in it.

If a single force acting on a body produces the same acceleration as produced by a number of forces, that single force is called the resultant of these individual forces. The resultant force is also called the net force.

Condition when more than two forces are applied over an object:

1. Forces applied in same direction: When more than one force is applied in the same direction, the total force is the sum of magnitude of both the forces.

Illustration: It is difficult to push a car by single person, but two or more persons can collectively push the same car easily.

This is because when more than one person tries to push the car, magnitudes of forces applied by each of the person are summed up and applied over than car, and car is pushed easily because of greater magnitude of force. That means if 3 unit force are applied over an object by each of the two persons,

The total unit of force = sum of both forces = 3 unit + 3 unit = 6 unit.

2. Forces applied in opposite direction: When two forces are applied over an object from opposite directions, the total effective force is the difference of two forces.

Illustration: When two persons are pushing a box in opposite directions and the magnitude of both the forces is equal, then box will not move, because the difference of two forces will be equal to zero.

Let a person applying 4 unit of force in one direction and other person is also applying 4 unit of force in opposite direction on the same wooden box.

Therefore, the magnitude of total force = 4 unit – 4 unit = 0.

If one person is applying a force of 4 unit in one direction and another person is applying a force of 6 unit in opposite direction, Then total magnitude of force = 6 unit – 4 unit = 2 unit. Thus, force will act in the direction of larger magnitude of force.

Balanced and Unbalanced Forces:

When the net effect produced by number of forces acting on a body is zero, then the forces are said to be balanced forces. If the two forces balance each other, they must be in opposite direction and have equal magnitude. For e.g., In a tug or war, when both the teams apply similar force from either sides, rope does not move, that is the resultant force is zero. Hence, it’s a balanced force.

When the net effect produced by a number of forces acting on a body is non-zero, then the forces are said to be unbalanced forces. For e.g., a boy pushes the refrigerator with a small force, the refrigerator does not move due to friction force acting in opposite direction to the push. If he pushes harder, the pushing force becomes bigger than friction force; the refrigerator starts moving in the direction of push.

.... (More Text Available, Login?)

Sample Questions

(More Questions for each concept available in Login)

Question : 1

External forces
A. are always balanced
B. never balanced
C. may or may not be balanced
D. none of these
Right Option : C
View Explanation

Question : 2

In which of the following cases the net force is not equal to zero?
A. A kite skillfully held stationary in the sky	B. A ball falling freely falling from a height	C. A helicopter hovering above the ground	D. A cork floating on the surface of water
Right Option : B
View Explanation

Question : 3

Which of the following are correct ? (a) The measure of amount or strength of force is called the magnitude of force. (b) If a set of forces acting on a body produces no acceleration in it, the forces are said to be balanced. (c) If a set of forces acting on a body produces a nonzero acceleration, the forces are said to be unbalanced.
A. Only (a) and (b) is correct .	B. Only (b) and (c) is correct .	C. Only (a) and (c) is correct .	D. All of these .
Right Option : A
View Explanation