1-mavzu: kirish. Mexanika bo’limlari. I-mashg’ulotning maqsadi

VI. MAVZUNING QISQACHA MAZMUNI:
Kuchning jismni ko’chirishdagi ta’sirini xarakterlash uchun ish tushunchasi kiritiladi. Ish F kuchni vektor bilan xarakterlanaligan dS ko’chishga skalyar ko’paytmasi bilan o’lchanadi. Juda kichik dS ko’chish uchun dAF'dSFdScos , (6.1)
bu yerda - kuch bilan ko’chish orasidagi burchak.
Ma’lum yo’lni bosilganda bajarilgan ishni topish uchun (6.1) ni butun yo’l bo’yicha integrallash kerak:
A∫FcosdS , (6.2)
bu yerda Fcos - harakatlanuvchi kuch.
Agar F kuch dS ko’chishga perpendikulyar bo’lsa, ish nolga teng bo’ladi. Agar jism to’g’ri chiziq bo’yicha doimiy kuch ta’sirida harakatlansa, ish quyidagiga teng bo’ladi:
AFSsos, (6.3) Burchak =0 bo’lsa, ish shunday ifodalanadi:
AFS. (6.4) Ish birligi XBS da 1Joul. 1J1N*1m.
Vaqt birligida bajarilgan ishga quvvat deyiladi. quvvat birligi 1 vatt. 1Vt  1J/1c.
Ish tushunchasi bilan energiya tushunchasi juda yaqin bog’langan. Energiya jismni yoki jismlar sistemasini ish bajarish kobiliyatini xarakterlaydi. Energiya ham XBS da Joul birligida o’lchanadi. Mexanik energiya ikki — potensial va kinetik energiyalardan iborat.
Kinetik energiya jismning harakati bilan bog’langan energiyadir va u jism tezligiga bog’liq bo’ladi:
mV ²
E_kin  . (6.5)
2

Kinetic Energy

The technical term for the energy associated with motion is kinetic energy, from the Greek word for motion. (The root is the same as the word“cinema” for motion picture, and in French the term for kinetic energy is “énergiecinématique”.) To find how much kinetic energy is possessed by agiven moving object, we must convert all its kinetic energy into heat energy,which we have chosen as the standard reference type of energy. We could dohis, for example, by firing projectiles into a tank of water and measuring the increase in temperature of the water as a function of the projectile’s mass and velocity. The proportionality factor equals 0.5 because of the design of the metric system, so the kinetic energy of a moving object is given by

The metric system is based on the meter, kilogram, and second, with other units being derived from those. Comparing the units on the left and right sides of the equation shows that the joule can be reexpressed in terms of the basic units as kg.m²/s². ⁵[6]