Force: Definition, Types, & Fundamentals

Overview

Force is a mathematical representation of an interaction that results in a change in the movement of an item. In reaction to a force, an item may accelerate, decelerate, or change its direction. In other words, its definition in physics is any activity that seeks to sustain or alter a body’s movement or deform it. Under force definition, the objects can be pushed, pulled, or can change their shape by applying external pressure. 

Define Force

What is force: It is an action that alters or sustains the movement of an object or a body. It is a pull or a push. It can modify an object’s direction, speed, and even structure. For instance, opening a door, closing a drawer, stretching a rubber band, and pressing the ball require applying force.

So, what is force? It is a vector quantity, meaning it has direction and magnitude. Though forces cannot be seen virtually, they can be monitored or measured in terms of a vector quantity. It can be measured in terms of using metres. The SI unit for force measurement is represented by the letter N, Newton, named after the English physicist Isaac Newton. Today whatever the world knows about its definition is based on Newton’s three fundamental laws of motion.

Newton’s Three Fundamental Laws of Motion 

In his three fundamental laws of motion, Sir Isaac Newton first articulated the concept of force. He defined gravity as an attracting force between objects with mass. Gravity, according to Einstein’s general relativity, does not need force.

Newton’s First Law of Motion states that until subjected to an external force, an object will proceed to move at a constant pace in the same direction. An item remains in motion unless acted upon by an additional force. It is called inertia. The object would not accelerate, decelerate, or change its direction unless some external force was applied to them. For instance, if a person glides a hockey puck across the ice, it will gradually come to a halt due to friction.

Newton’s Second Law of Motion states that force is exactly proportional to velocity (change in the rate of momentum) for the same mass or weight. In the meantime, acceleration is (inversely) oppositely proportional to mass or weight. For instance, when a person throws a basketball onto the surface, it generates a downward force on the ground, exerting an upward force and causing the basketball to bounce. Students can use this law to calculate forces. Students can compute the third factor if they know the first two. Students can also understand that if an object accelerates, a force must be operating on it.

Newton’s Third Law of Motion is concerned with the interactions of two objects. The law explains that there will always be an equal and opposite force to every action (activity). Whenever a force is exerted on one object, the object also exerts the same impact as the force itself, but in the reverse direction. If a person sails a paper boat into the water, the energy a person uses to propel the paper boat forward will also propel the paper boat backward. The action and response forces occur together.

Kinds of Forces

This can be classified into two major categories. These are contact forces and field forces.

Contact Force

It occurs when two or more items or bodies immediately come in contact. There are two common types of contact forces. These are friction and elastic forces. Other than these, air resistance is the third type of contact force.

• Friction Force

This is a type of force that restricts relative movement between two commodities that comes in contact with one another. The frictional force between the floor and shoe soles resists a person’s forward motion while walking on the ground. Friction acts in the opposite direction of an object’s motion. When a person pulls a chair, they use force to propel it forward. Here the floor generates a frictional force to prevent the forward motion of the chair.

Rough surfaces have substantially higher friction than smooth surfaces. For instance, wearing metal skates rather than rubber boots makes it simpler to skate across ice since the friction between ice and metal is less than that between rubber and ice.

• Elastic Force

These are the forces that can change the shape of an object. When a person stretches an elastic band’s ends, it extends and resists getting stretched. The forces between the molecules of the elastic rubber band cause resistance. Similarly, when a person crushes a ball made of clay, the force lying between the components resists the ball from crashing altogether. Elastic forces are the forces where a commodity exerts resistance to its change in shape; this resistance is communicated through the molecules of the commodity. There are two types of elastic forces: compression and tension.

• Air Resistance Force

Air resistance is the frictional force that air exerts against a moving body. Air resistance reduces an object’s movement. The stronger the air resistance against a body, the faster it moves. Air resistance impacts all moving bodies, including aeroplanes, trains and rockets, automobiles, bikes, and even living organisms.

Air resistance can entirely increase or decrease depending on the surface area and shape of the object. For instance, a bird feather has a larger surface area than a metal ball and thus, will drop more slowly. A bird’s feather experiences more air resistance and drops because it can distribute its weight over a bigger area. The same principle applies to a parachute.

Field Forces

Four elementary forces govern the interactions of physical phenomena. Scientists are still working on developing a theoretical model on them:

• Gravity

Gravitation is the force acting between two masses. Gravity exerts its force on all objects. For instance, if a person holds a football in the air, the mass or weight of the Earth enables it to descend due to gravity. If a baby butterfly crawls out of its egg, the Earth’s gravity will draw it to the ground. The graviton has been hypothesised as the object that mediates gravity. However, it has yet to be discovered.

• Electromagnetic Force

The electromagnetic force is a force that acts between electrical charges. The photon is the intermediary particle. For instance, if a loudspeaker employs electromagnetic forces to transport sound, its locking system uses electromagnetic forces to assist close vault doors snugly. Power circuits in surgical instruments, such as electromagnetic forces, and magnetic resonance imaging, as do magnetic rapid transit facilities in China and Japan, are referred to as “maglev” for magnetic levitation.

• Strong Nuclear

The strong nuclear force is a type of nuclear force that keeps the atom’s nucleus united, mediated by subatomic particles acting on antiquarks, quarks, and the gluons themselves. (A gluon is a substance that connects quarks within neutrons and protons.) Quarks are elementary particles that unite to produce neutrons and protons, whereas antiquarks have the same mass as quarks but have opposing magnetic and electric properties.)

• Weak Nuclear

The weak nuclear force is a type of nuclear force mediated by the exchange of Z and W bosons, shown in the nucleus of beta decay of neutrons. (A boson is a sort of entity that follows the Bose-Einstein statistics principles.) The electromagnetic and weak forces are interchangeable at very high temperatures.

Conclusion

After reading the article, students would be able to define force properly. When a commodity is pulled or pushed due to the interaction with another commodity, it is termed force. Its definition states that when two commodities interact with each other, a force is exerted on both of the commodities. When the interaction ends, the two commodities no longer feel the force. It can exist exclusively as a consequence of the interaction between the objects.

Frequently Asked Questions 

1. Explain the relationship between force, pressure and area.

Ans. Pressure is the amount of force operating on a specified surface area. There is a mathematical or quantitative relationship between force, pressure and area:

pressure = force / area

This relationship has a wide range of practical uses. For instance, when a force is applied to a tiny region, it creates more pressure than the original force applied to that area. Students can best understand it: walking in deep snow with snowshoes is much easier than walking with boots because the snowshoes distribute the overall body weight’s force over a greater surface area.

2. What is force, and explain its impact.

Ans. A force is just a pull or pushes in one direction. These are created when one item interacts with another. There are various impacts of force applied on a particular object; some of these are listed here.

• It can cause a still body to move.
• It can either slow or stop moving the body.
• It can increase the velocity of a moving body.
• It can also affect a moving body’s size, shape and structure and direction.

3. What is a Force Line of Action?

Ans. The force’s line of action is the line across which a force acts on a component. The point at which a force acts on a component is referred to as the point of application of a force. The force of friction is the force that resists the relative motion of two surface materials and interacts along with the interfaces. The net force acting on a component is zero when all the forces operating on it are balanced.