Forces and Motion - Embibe Exams
• Written By Rumela_M
• Written By Rumela_M

Forces and Motion

In our daily lives, you have seen cars, scooters and different other vehicles parked at your garage or in the parking zone at different shipping malls. The traffic that we see on the roads is because of moving cars and autos. Yes, you have to apply brakes in the car to cause it to stop after you have driven them for a considerable distance. But what actually takes place behind applying the brakes that cause the cars to stop?? Or let us look at an alternative situation.

When a car is already at rest, what causes it to come to a state of motion? The whole principle that brings in a change in the object’s existing state, is Force. In other words, Force is the application of an external pressure that brings an object to a state of rest from its existing state if motion, or to a state of motion if it was in a state of rest. In this article, we will understand what is Force, what does it do, what is motion, how are the two related and more. This will help to build your understanding on the concept of Force and Motion.

What is Force?

According to the Universal Law of Gravitation, when multiple objects are in contact with each other, one object exerts a force on the others. The expression that force is acting on an object, is represented by the following parameters:

• The SI unit of Force is newton(N) or kg.m/s2
• The dimensional formula for Force is M1L1T-2
• The other units of force are dyne, pound-force, poundal, kip and kilopond.
• The symbol of force is denoted by F
• Force is a vector quantity

Force is a push or pull that acts on an object, or on energy, as an attribute of physical action or movement. That is to say, force is what causes the interaction between two or more bodies when they are in contact with each other.

Let us say that there are two objects. One has a mass ‘M’ and another has a mass that is represented by m. These two objects are positioned in such a way that the object which has a mass of ‘m’ rests over a body with a mass ‘M’. In terms of Physics, we say that the two bodies exert a force on one another. Whenever two or more objects interact with one another, the underlying reason that causes interaction between these two bodies, is Force.

What is Motion?

When a body is moving, it is said to be in a state of motion. Let us understand this with the help of an example.

Suppose someone is walking up the street from home to the shopping mall. In this instance, the person in reference is in a state of motion. Let’s say instead of walking all the way from home to the shopping mall, the person meets a friend on the way and stops for a while to talk to the friend or to buy a bottle of water from a nearby store and take some rest. During this time, will the person be in a state of motion? No. Hence, we can say that the motion of a living being or a non-living object is dependent on time. Thus, motion is the change in the position of an object or a body with respect to time.

Relation Between Force and Motion

The concepts of Force and motion are interrelated. Force is the causal factor behind motion. When something is moving, it is because of some force that is acting on it, that causes this motion.

If someone is walking, the person is said to be in a state of motion. There has to be some force acting on the person that is causing movement in him or her. It is the muscular force of the body of the person, that is causing movement. This is why we define force as, “an interaction, that when opposed, will change the motion of an object.” Thus it is clear from the definition that force affects the state of motion of an object.

The relationship between force and motion is expressed by Newton’s second law of motion. In terms of formula, Force is expressed as the product of mass and acceleration.

Force (F) = Mass (M) * Acceleration (A)

We have already stated that motion is the change in position of an object with respect to time. Motion refers to the movement of a body. Hence we can infer two things about motion, which are as follows:

• Motion is the change in speed
• Motion is the change in direction.

What Can Force Do?

The first person who discovered the relation can exist between force and motion was Sir Isaac Newton. Upon studying force and laws of motion, he derived three conclusions:

• Force can cause acceleration in the body = When force is applied on a body that is in its state of rest, and there is no other bigger force that is opposing it, the body that was in the state of rest, starts to move. Let’s take an example of a bowler throwing a ball towards the batsman while playing cricket. The ball starts to move forward from its initial position of rest towards the batsman. Something is moving from its state of rest, it accelerates. Acceleration can be defined as a positive change in velocity over a period of time.

In a similar line, if the body was in the state of motion, and the force was applied in the same direction of movement with no other greater force opposing the same, it will accelerate. For instance, on rotating the pedals of a bicycle, the bicycle runs faster.

• Force can cause deceleration in a body = In an alternate case with regard to the same situation, if force is applied on a direction opposite to that of the moving object, it will either slow down or decelerate or entirely stop, if the force continues to be applied on the object. For example, if the batsman hits a sixer, but the wicket keeper catches the ball, he has caused the moving ball to decelerate and stop.
• Force can cause the direction of a moving body to change = When force is applied on an object in an angle which is not similar to its direction of motion, it causes the object to change motion. In this case the speed of the ball can be maintained, if the force is applied on the ball in a perpendicular angle. However, in this case, the velocity of the ball will change

We hope that this information on Force and Motion has helped you. If you have any queries, you can visit our website and write to us with your queries and we will answer your queries in the best way possible. Stay tuned to Embibe for the latest news and updates.

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