Question

বিভবশক্তি বলতে কী বোঝায়?

Answer 1

স্বাভাবিক অবস্থান থেকে পরিবর্তন করে কোনো বস্তুকে অন্য অবস্থানে বা স্বাভাবিক অবস্থা পরিবর্তন করে অন্য কোনো অবস্থায় আনলে বস্তু কাজ করার যে সামর্থ্য অর্জন করে তাকে বিভব শক্তি বলে। বিভব শক্তিকে Ep, দ্বারা প্রকাশ করা হয়। কোনো বস্তুর মধ্যে সঞ্চিত বিভব শক্তি অভিকর্ষজ ত্বরণ (g) এবং ভূমি হতে বস্তুর উচ্চতা h এর উপর নির্ভর করে। পৃথিবী পৃষ্ঠ থেকে m ভরের কোনো বস্তু h উচ্চতায় অবস্থান করলে উক্ত বস্তুর মধ্যে সঞ্চিত বিভবশক্তি, Ep = mgh.

Answer 2

Kinetic energy, a form of energy that an object or a particle has by reason of its motion  If work, which transfers energy, is done on an object by applying a net force, the object speeds up and thereby gains kinetic energy. Kinetic energy is a property of a moving object or particle and depends not only on its motion but also on its mass. The kind of motion may be a translation (or motion along a path from one place to another), rotation about an axis, vibration, or any combination of motions.

The translational kinetic energy of a body is equal to one-half the product of its mass, m, and the square of its velocity, v, or ¹/₂mv².

This formula is valid only for low to relatively high speeds; for extremely high-speed particles it yields values that are too small. When the speed of an object approaches that of light (3 × 10⁸ meters per second, or 186,000 miles per second), its mass increases, and the laws of relativity must be used. relativistic kinetic energy is equal to the increase in the mass of a particle over that which it has at rest multiplied by the square of the speed of light.

The unit of energy in the meter-kilogram-second system is the joule. A two-kilogram mass (something weighing 4.4 pounds on earth) moving at a speed of one meter per second (slightly more than two miles per hour) has a kinetic energy of one joule. In the centimeter-gram-second system, the unit of energy is the erg, 10⁻⁷ joule, equivalent to the kinetic energy of a mosquito in flight. Other units of energy also are used, in specific contexts such as the still smaller unit, the electron volt on the atomic and subatomic scale.

For a rotating body, the movement of inertia, I, corresponds to mass, and the angular velocity (omega), ω, corresponds to linear, or translational, velocity. Accordingly, rotational kinetic energy is equal to one-half the product of the moment of inertia and the square of the angular velocity, or ¹/₂Iω².

The total kinetic energy of a body or a system is equal to the sum of the kinetic energies resulting from each type of motion.