This concept is just as it sounds. In short, a work that doesn’t happen. The concept of virtual work becomes convenient when the angle between the tension the direction of virtual displacement is either zero or 180. Thus, in a sense, it can be said that the concept applies to 1 degree of freedom systems.
Material science has always a topic of research and fascination, about how a single atom has so many properties that can alter the whole tensile as well as the ultimate strength of a material such as cement or concrete which is used build skyscrapers …yes the same you watch in Hollywood movies.
What is the difference between moment and torque is the question that pops up in most of our minds?
In physics, they signify the same thing but in mechanics, they hold slightly different meanings. Both have the same unit i.e. N-m but torque is a movement force whereas the moment Is a static force. Torque is used where there is rotation involved whereas moment Is used where there is no rotation.
Application of moment and torque for varied and interesting to observe. I hope everyone has played on a seesaw at least once in their life. What if I tell you that you can keep the saw balanced by having a 120 kg person one side and a 50kg person on the other side?
It seems difficult to accept but if you place them in such a way that the lighter person is at 3m from the center and the healthy person is at 1m. They both will apply the same moment and the seesaw will be balanced.
In rural areas, people still use the concept of the moment to churn milk. By providing a torque to the handle with the help of the rope the wooden stick rotates about its axis and thus, in turn, churns the milk.
A similar concept of torque is used in old dams where the force of the falling water rotated the water wheel. The water wheel was connected to a dynamo thus generating electricity by the principle of conversion of kinetic energy into potential energy.
The International System of Units (SI)has become the fundamental basis of scientific measurement worldwide. This system is an extension and refinement of the metric system, which is more superior and convenient than other systems. It provides one basic unit for each physical quantity. So, the 7 units of measurement are follow
The basic fundamental unit of mass is “Kg”. We also measure mass in Gram, Pound, Metric ton, Stone, Microgram, Carat, etc.
The basic fundamental unit of Time is “Sec(s)”. We also express time in seconds, minutes, hours, days, weeks, years, etc
3. Electric Current –
The basic fundamental unit of Electric Current is “Ampere(A)”.
4. Amount of Substance –
The amount of Substance is a dimensionless expression of the number of particles in a particle or object. The basic fundamental unit of Amount of Substance is “Mole”. The amount of substance all called material quantity.
The SI unit of Illumination is “Candela”. Candela is denoted by symbol ‘cd’. Some other units are lux, lumen, etc.
The SI unit of Distance is “Meter”. Distance also measures in mm, cm, km, yard, inch, foot, feet, etc.
The SI unit of temperature is “kelvin”, expressed as the word “K”.Temperature 0 K is known as “absolute zero.”
We use two types of scale in measuring temperature that is –
1.Relative scales [Fahrenheit (°F) and Celsius (°C)]