Work and Energy Lecture Flashcards

Vocabulary flashcards covering fundamental concepts, definitions, formulas, and historical figures from the lecture on Work and Energy.

Work (Physics)

The product of the magnitude of the applied force and the displacement of the object in the direction of the force, represented as Work = Force $\times$ Displacement.

Work Done at an Angle

The work done when the applied force $F$ makes an angle $\theta$ with the horizontal displacement $s$, given by the formula $W = F s \cos(\theta)$.

Joule

The SI unit of work; defined as the amount of work done on an object when a force of $1\,\text{newton}$ displaces it by $1\,\text{metre}$ in the direction of the force ($1\,\text{joule} = 1\,\text{N} \times 1\,\text{m}$).

Erg

The CGS unit of work; defined as the amount of work done when a force of $1\,\text{dyne}$ displaces an object through $1\,\text{centimetre}$ in the direction of the force ($1\,\text{erg} = 1\,\text{dyne} \times 1\,\text{cm}$).

Relationship between Joule and Erg

The quantitative equivalence between SI and CGS units of work, where $1\,\text{joule} = 10^7\,\text{erg}$.

Positive Work

Work performed when the direction of the applied force and the direction of displacement are the same ($\theta = 0^\circ$).

Negative Work

Work performed when the direction of the applied force and the direction of displacement are opposite to each other ($\theta = 180^\circ$).

Zero Work

Work done when the applied force does not cause any displacement or when the force and displacement are perpendicular to each other ($\theta = 90^\circ$).

National Physical Laboratory, New Delhi

An institute conceptualized in 1943 operating under the Council of Scientific and Industrial Research, whose main objective is to establish national standards of physical quantities and conduct basic physics research.

Energy

The capacity of a body to perform work, measured in joules in the SI system and ergs in the CGS system.

Kinetic Energy

The energy an object possesses because of its motion, calculated by the expression $K.E. = \frac{1}{2} m v^2$.

Potential Energy

The energy stored in an object because of its specific state or position, expressed mathematically as $P.E. = m g h$.

Law of Conservation of Energy

The principle stating that energy can neither be created nor destroyed, but can only be converted from one form into another, keeping the total energy in the universe constant.

Free Fall

The motion of an object falling solely under the influence of the gravitational force.

Power

The rate at which work is done, expressed mathematically as $\text{Power} = \frac{\text{Work}}{\text{Time}}$ ($P = \frac{W}{t}$).

Watt

The SI unit of power, equal to $1\,\text{joule}$ of work performed per $1\,\text{second}$ ($1\,\text{watt} = 1\,\text{joule}/1\,\text{second}$).

Horse Power

A unit used to measure power in the industrial sector, equal to $746\,\text{watt}$.

Kilowatt Hour (kWh)

The commercial unit of energy corresponding to $1000\,\text{joule}$ of work performed per second for 1 hour, equal to $3.6 \times 10^6\,\text{J}$ or $1\,\text{unit}$.

James Watt

The Scottish scientist (1736-1819) who invented the steam engine in 1781 and was the first to use the term 'horse-power'.