Forces and Motion: Definition and Unit

Have you ever wondered why a ball rolls away when given a little push or kick? It is due to the force that is given to the ball. Force is defined as a push or pull on any object. Force is known to impart motion to the object. The action of being moved or mobilised from one point to another is called motion. Either way, you can say that motion on an object happens due to force.

So, the next time you see an object moving, think that some force from behind is causing it to move. When force is applied to a moving object in the same direction, the object’s speed increases, but if force is applied the opposite way, the object’s speed decreases. Similarly, the state of motion of an object also varies. Wondering how? Keep reading this article.

Force and Motion: Overview

Both force and motion are interrelated with each when it comes to Physics. The direction of motion, as well as speed, describes the state of motion. However, before getting into how this happens let us understand the complete overview of both the physical entities.

Contact Forces are the ones when one object is in contact with another. Some real-life examples are riding a bicycle where the pedal touches the foot of the person, passing a football when the foot touches the ball, an aeroplane flying through the air, and more. 

On the other hand, Non-contact forces are not having any criterion of an object in touch with one another. Some daily life examples are magnetic fields across the north and south poles, X-rays applied across the human body to take photo prints of internal organs, and more.

Now that you have understood the fundamental difference between forces and motion let us help you in giving the interrelationship between these two physical entities, which are essentially a part of our daily life.

Interconnection Between Force and Motion

In nature, force and motion are related to each other. In simpler terms, force is the cause of motion. If any of the objects are moving, we usually say that some force is acting on them. When an object falls through a vacuum, it is solely subjected to one external force: gravity, which is quantified as the object’s weight.

If a man is walking and thus in motion, he must be subjected to some force that is causing him to move. So, what exactly is this force? It is his body’s muscular force. Force is neither a push nor a pull, to put it another way. It’s defined as “any interaction that, while uncontested, causes an object’s motion to alter.” It is evident from the definition that force has an effect on an object’s state of motion. Furthermore, motion is defined as a change in location over time.

Force expression is related to mass and acceleration since it is denoted as,

F=ma

Over here,

m=mass of the object
a= acceleration imposed on the object

More Details on Force and its Types

Mathematical Relation Between Force and Motion

As per Newton’s second law of motion, there exists a mathematical expression between force and motion. It is given as:

Over here,

s = position of the object
s₀ = initial position of the object
v₀ = initial velocity of the object
a = acceleration
t = time

There can be acceleration, deceleration, change in direction, or total cessation of motion happening due to force. So, for explaining distance and displacement, terms of motion can be used accordingly.

Questions on Forces and Motion

You must have gained all the basic necessary information regarding Force and Motion in this article. Now, let us give you some MCQs on the same which you can solve on your own:

Q1. What can a force change?

A. Speed, shape and colour of an object
B. Speed, shape and direction of an object
C. Speed, shape and elements of an object

Q2. What is the unit of force?

A. Newtons
B. Einsteins
C. Keplers

Q3. When an object is in motion, what direction does friction act in?

A. The same direction as the motion of the object
B. At right angles to the motion of the object
C. The opposite direction to the motion of the object

Q4. What are balanced forces?

A. Forces where the effect of one force is cancelled out by another
B. Forces where the effect of one force is larger than another
C. Forces measured using a Newton balance

Q5. What unit is motion measured in?

A. Kilograms
B. Newtons
C. Metres per second per second

We hope that this comprehensive article on ‘Forces and Motion‘ has been assistive and provided you with insights into the physical entities of daily life and more. 

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