10 Science Principles You See in Action Every Day

#5

 Forces:

You may not know but forces are everyday life movements, by reading a book, talking, running andwriting on a page you are applying a force. They cause objects to move or stay stationary.Forces are vector quantities: they have both a magnitude and a direction.

Many things can cause forces (our muscles, car engines, springs, the gravitational pull of the Earth), in Nature there are only four fundamentally distinct types of forces. In fact in our daily lives we only directly experience two of these forces: electromagnetic forces and gravitational forces. Electromagnetic forces we usually experience as two very different phenomena. Electric, or electrostatic forces, cause the sometimes painful sparks that we feel when touching a metal object after walking across a wool carpet in bare feet. Magnetic forces cause the magnet in a compass to point towards the North Pole. It was Maxwell who first showed that electrostatic and magnetic forces are two different manifestations of one and the same phenomenon, so they are now often referred to by their common name: electromagnetic forces. Electromagnetic forces hold the electrons in orbit around the nuclei in atoms, and, as the name suggests, they also provide the basis for many of the modern ``electronic'' gadgets (radios, TVs, microwaves, computers) that we currently take for granted. Our most direct experience with electromagnetic forces comes from the fact that they are responsible for holding together the molecules that make up solid objects. Thus electromagnetic forces are also the source of the ``repulsive'' contact forces we feel when we touch or hit solid objects. Electromagnetic forces keep you from falling through the chair that you are sitting on while you read this.

The other force most important to our daily lives is gravity. It is what pulls us towards the Earth and keeps us from drifting off into space. It also keeps the Earth and other planets in orbit around the Sun. So your ability to sit motionless on the chair while reading this is caused by a balance between gravity, which is trying to pull you down, and the electromagnetic forces that hold the molecules of the chair together and keep you from ``bursting'' through it.

There are two other fundamental forces that we do not directly experience. The so called ``strong'' force holds the nucleus of the atom together. It is very short range, and cannot be felt even by the electron orbiting the nucleus. However, under the right conditions, the energy of the nuclear force can be unleashed with startling consequences, as in the case of nuclear bombs, and nuclear power plants. The fourth force is called the weak force. It is primarily responsible for the reactions in the Sun that give rise to the radiation (heat and light) that keeps us alive on Earth.

Thus, it should be clear that even though we only have direct experience with electromagnetic and gravitational forces, life on Earth depends in a crucial way on the presence, and delicate balance between, all four forces.

Examples of force abound in daily life. There is force working all around, for eg. :

(1) (i)When we walk, we put force on the ground

      (ii) When we stand say, say with a load on our head, then also we exert force on the ground.

(2) When we push open the door , we apply force on it.

(3) Two team of the players are pulling with enough force the rope in a tug of war game.

(4) We jump and come back to earth.(gravitational force)

(5) Spinning a football on your finger. 

(6)A football is kicked harder. It moves faster later after some time its force decreases due to friction.

(7)A moving bike stops when brakes are applied.

(8)Attractive forces between the bodies in universe

(9)Gravitational force attracting the ball moving up.

(10)A bull is pulling the cart due with force.

(11)A boy put his drawing paper by inserting a board pin with it on the notice board.

(12)Squeezing of wet clothes to make it dry.

(13)A glass rod is rubbed with silk so that it attracts the tiny parts of the paper towards itself.   

The image above shows an artist's rendition of a flow of events in a 13-billion year history of the Universe from the Big Bang at upper right counter-clockwise to the formation of life on Earth at lower right.