# Concepts of Force and Motion in Physics

### Concept of Force:

Force is defined as any form of push or pull acting on an oobject. It is a vector quantity because it has both magnitude and direction. You may have heard a saying that goes thus:

• what goes up must come down.

The above statement is true because the earth has a force acting upon it. This force, (called the gravitational force of the earth) acts by pulling all things towards the earth.

In order to move away from the earth, there must be another constant force acting on an object that attempts to exit earth's surface. This force must be greater than the earth's gravitational force (or force of gravity). For this reason, aeroplanes and jets move away (fly) from the earth and remains in the sky because the constantly applied force on them is greater that the earth's gravitational force.

In another instance, when you jump, you apply a force. However, since this applied force isn’t constant, the force of gravity present on earth eventually bring you back to earth's suface.

Force as a quantity is measured in Newton (N). This is in honor of Sir Isaac Newton for the great work he had done.

Force can be balanced or unbalanced. When forces from different directions act on an object and consequently bring about the object's motion, then such forces are unbalanced. Conversely, if theses forces bring about zero motion (static position or no movement) on the object of reference, then it's a balanced force. To summarize this:

• An apple hanging on a tree (without any form of movement) has a balanced force.

• An apple falling from a tree has an unbalanced force.

### Force and Motion:

Sir Isaac Newton presented the laws of motion which was accredited to his name in 1968. These motion laws of Newton explains the relationship between the forces acting on a body and the motion of the body.

Recall that motion refers to a change in the position of an object with reference to time. As an instance, a pen resting on a table will continue to remain on the table unless it is pushed or pulled by something. This push or pull with the tendency of making the pen move away from its exact position is termed force.

Force exists as a result of an interaction between two objects. From the above instance, if nothing interacted with the pen on the table, then the pen will continually remain on the table. In summary, always understand that if there is no interaction between objects, force will never be experienced.

With the above explanation on force and motion, we can now understand more easily the Newton's laws of motion. 