Force and Motion: Relation, SI Unit, Formula

We define force as that external push or pull acting on an object which changes or tends to change the state of rest or state of a uniform linear motion of the object. A  force may also deform an object. In physics, we encounter various body movements. What causes the movement of an object? The answer is powerful. What is stopping the moving object? The answer is Force. Thus, in general, force and motion are similar to the two sides of a coin. For example, the relationship between force and movement is seen in throwing a ball and catching the ball.

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Definition: Force and Motion

To understand what force is, we need to think about gravity. Pushing and pulling apply to an object or force such as movement or an attribute of physical activity is defined as a force. It is like pushing and pulling, words like squeezing and stretching also define the concept of what energy can do. This is especially so when two parties are in contact. Based on Newton's universal law of gravity, everything in the universe has been forced over other things. Thus, a force may start motion in an object which was at rest. The SI unit of force is Newton (N) or kg.m/s². The measuring quantity of force is a ‘vector’.  

Force is associated with the motion of translation when an object is moving in a certain direction. However, under such conditions, energy can transform an object into a specific axis. This is known as the turning effect of a force. 

In simple terms, whenever the body moves, we say that it is in motion. For example, if a boy is walking down the street from the school to home, we could say that the boy is moving. But imagine if a boy stops for 5 minutes on the road and sits down. If someone immediately asks if the boy is moving, the answer will be ‘no’. In this regard, we can conclude that physical activity is time-dependent. In physics, we say that movement is a change in a physical state in terms of time. 

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SI Unit of Force - 

The SI unit of moment of a force is Newton or newton metre (N m).

Also Read: Unit of Force

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Relationship between Force and Motion

Force and motion are closely linked with nature. We can say that force is the cause of movement. Suppose there is a movement, we can say that there must be some force at work or there must be some force at work that produces this movement. When a person is walking, therefore moving, there must be some active force in it that makes him move. What is this force? This force is the muscle strength of his body.

Before we get into the relationship between force and movement, let’s take a quick look at what energy means. Simply, a force can be pushed or pulled. Force is defined as ‘any interaction that, if not challenged, will change the movement of an object.’ By the definition itself, it is clear that the force affects the state of the movement of an object.

But what exactly does a state of motion mean? In physics, motion is defined as a change in position relative to time. In simple terms, movement refers to physical activity. In general, motion can be defined as,

• Change the speed, though
• Change direction.

Sir Isaac Newton was the first to discover the link between motion and force. From his practical lessons and the laws of motion we can come to the following three conclusions:

• Force can speed up the body
• Force can change the direction of a moving body

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Force and Motion Formula 

From Newton’s second law of motion, we can define the relationship between force and motion mathematically as:

F = m.a

Thus, force is defined as the product of mass and acceleration. 

Motion: It is defined using the laws of motion and is defined as the behavior of particles during movement and it is expressed as,

s = s₀ + v₀t 1/2at²

s = position of the article

s? = initial position of the particle

v? = initial velocity of the particle

a = acceleration

t = time 

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Things to Remember 

• Application of force can make a body at rest move.
• Force can change the direction of the moving object.
• The turning effect is either clockwise or anticlockwise. 

Force can be given as: F=ma and motion is given as: s = s₀ + v₀t 1/2at²

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