We are living in the century of science and technology and introduction of science in our daily life has transformed our lives. When people had no idea about science, even then their lives were governed by principles of different branches of science. When we light a fire, it is a chemical process; when we eat and digest food, it is biological process; when we walk on Erath, it is governed by laws of physics; when an Earthquake occurs, it’s a seismic activity; when we talk about different terrains and gems of Earth surface, it is related to Geology. There is no single activity of our lives, which define our one or other field of science. Similarly, physics governs our everyday lives and is involved in a number of activities we perform and things we use in our daily life. Here we will discuss how physics is playing its part in running our everyday tasks and assists us to do our errands, chores and duties smoothly and effectively.
Physics is considered natural science because it deals with the things like matter, force, energy and motion. As these all are related to task related to everyday life, so, we can say that physics studies how the universe works, how Earth Moves around the sun, how lightening strikes, how our refrigerator works and many more. In short, physics define how everything works around us. When cannot separate anything from science and, our world cannot disconnect itself from the wonders of Physics. When we look around us, we can see a number of things that work on the principles of Physics. We can explain our several activities by making use of the knowledge of Physics.
A number of principles of physics are involved in simple act of walking. It involves concepts of weight, Newton’s three laws of inertia, friction, gravitational law and potential and kinetic energy. When we walk, we actually act like an inverted pendulum. When we put the foot on ground, it becomes our axis and our mass is centered in our abdomen, describing the shape of an arc. When we set foot on ground, we actually put weight i.e w=mg and apply backward force on ground, as the response to our weight, ground responds by an opposing force which is vertical in nature, on leg which slows us down and this slowing process continues unless our leg comes nearest to our tummy. When leg is moving, kinetic energy is at maximum and potential energy is zero, but, when leg reaches nearest to belly or arc, potential energy reaches to its maximum. When another step is taken, the stored potential energy is converted to kinetic energy and this process continues. We act as an imperfect pendulum, because all potential energy is not converted into kinetic energy. Only 65 percent of energy is provided by stored potential energy to take next step, remaining 35 percent is provided by bio chemical processes.
When we walk we actually do some work in physical terms, as W=F*S, when we exert some force and as a result of it we cover some distance we actually do work. During walking, Newton’s three laws of motion are applied. First law of motion states that, a body remains in state of rest unless a force is applied on it. When we are at rest, inertia is at maximum. Body needs largest amount of force to get out of state of inertia, i.e when we start walking. When we talk first step the energy is transferred from foot to upper body parts and we start moving, during the process of walking inertia keeps on changing, increases when we set foot on ground and decreases when we move the foot up. Second law of motion states that a=F/m i.e acceleration is directly proportional to the force we use or exert while walking, therefore, when we will apply more force, our acceleration will increase. Third law of motion is about action and reaction, when we set foot on ground we exert force on it and as a result to it ground exerts reactionary vertical force on body.
Thermodynamics is a branch of physics that deals with heat, temperature and work done due to it. Heat is a form of energy that can be transferred from one medium to another i.e heat transfer. For heat transfer, heat travels from hotter surface to cooler. When we put pan, with water or something else in it, on burning stove the energy in flame of stove touches cold pan, it starts transferring heat to the pan thus making it hooter. This phenomenon is called conduction. Convection is a process of movement of molecules in liquid and gases. When we heat the pan, the water molecules on the base of pan start heating up, a time comes when they get enough energy and become hotter than the molecules around them, then they start moving to the surface of water. The water molecules on the surface are cooler and heavier from hot water, due to less heat energy, thus start moving down, this process continues until all water comes at same temperature.
The cooking process is an open system, because in this both matter and energy is lost. According to zeroth law of thermodynamics energy should be conserved, in our case the energy lost by flame is used by pot to heat water and thus the total energy remains conserved. If we use pressure cooker it uses heat energy to bring spontaneous changes into food by using kinetic energy of molecules to bring chemical changes in food; thus satisfying law of thermodynamics that spontaneous works are done due to work energy.
CUTTING FRUITS AND VEGETABLES:
When we cut fruit and vegetable, we never realize that physics could be involved in this simple task, but, surely it is. In order to cut anything, we have to exert pressure on knife. When we increase the pressure we can cut an object easily. Pressure is dependent on force and area i.e directly dependent on force and inversely dependent on area. In simple terms we can say that when we exert more force we can cut an object easily, but, if same force is applied with a knife with thicker edges, we cannot it. From experiences we learn that the knives which have edges with smaller surface area can help to cut an object easily. Similarly, we can cut easily with a sharper knife than blunt. The blunt knife offers more friction, due to its rough edges; thus making it difficult to cut an object.
Our eyes are an incredible gift by God. We see wonders of the world, by this small organ. When we talk about parts of body and their function, it is the general concept that we are talking about biology. But, we neglect the fact that functions of our body parts are also working under the laws of physics and chemistry. If we talk about the sense of seeing, we come to know that our eyes work as a camera to see things around us. The lens in our eyes is convex i.e it converges or focuses light. When light enters our eye, cornea and lens focus the light. Iris controls the amount of light entering the eye and iris creates an image on retina, which is real and inverted i.e like in camera. The image of light is converted into electrical signal, by photoreceptors, and sent to vision centre of brain by optic nerve. The vision center analyses the electric signal and arranges it into its original form i.e to be seen by eye. The image we can see is due to the amount of light reflected from that object. This is the reason why we cannot see in dark.
Eye can perceive different shapes and colors of the objects. Light consists of seven colors, when it falls on an object say, book of color red, it absorbs all the colors and reflect red color. This helps us to interpret that the cover of this book is red. When light falls a white object then it reflects all the colors and that’s why it seems white (we also regard light as white light). Similarly, when light falls on black object it absorbs all the light and reflects nothing that’s why that object looks black.
OPENING AND CLOSING DOORS:
Physics is also involved in opening and closing of hinged doors. The phenomenon involved in opening and closing of door is torque. Torque is the force required to twirl an object about an axis or fulcrum. When we open a door by using the handle, at farthest place from hinge, we can easily open the door by producing torque, T = F * r * sin(theta), where r is the distance of hinge from door knob or handle.
If the knob is located near the hinge, we have to exert more torque, thus producing less angular acceleration. When we apply force perpendicular to the door, larger angular acceleration is produced. When we apply force on the door knob, compel the door to rotate on its axis thus acting on the principle of torque. Torque is positive when we open the door clockwise and negative if we open it anticlockwise.
Here, we have seen a limited example of physics, but over life is governed by this branch of science. Physics governs a lot of natural phenomenon and also define a number of man made things like cars, refrigerators, microwave and escalators. Hence, we can say that our world is ruled by physics.