BharatNotes Momentum
noun (plural momenta or momentums)Usage in a UPSC answer
Although the Swachh Bharat Mission generated remarkable early momentum through mass mobilisation, sustaining behavioural change demands that the impetus be institutionalised rather than allowed to dissipate once political attention shifts.
Synonyms
Antonyms
Word Family
momentum (n), momenta (n pl), moment (n), momentous (adj), momentously (adv), momentousness (n)
Root
Latin momentum = movement, contraction of movimentum; movēre = to move; -mentum = noun-forming suffix
Etymology
From Latin momentum, a contraction of movimentum, from movēre ("to move") + -mentum (noun-forming suffix).
Memory Hook
Linked to "moment" and "move" (Latin movere): once something is moving, each MOMENT adds to its MOMENT-um, building force that is hard to halt.
How This Word Works in UPSC Writing
The product of mass and velocity, and a vector, so direction is part of the quantity rather than incidental to it. Its importance lies in conservation: in the absence of an external force the total momentum of a system stays constant, which is what explains the recoil of a gun, the propulsion of a rocket that carries no medium to push against, and the outcome of every collision. It also corrects a common misstatement of Newton's second law, which is properly the rate of change of momentum rather than mass times acceleration, the familiar form being only the special case where mass is constant. The impulse relation, that change in momentum equals force multiplied by the time over which it acts, is the practical payoff: airbags, crumple zones, helmets and bending the knees on landing all work by stretching the same momentum change over a longer time, so the force is smaller.
Don’t Confuse It With
Momentum is mass times velocity and is a vector, while kinetic energy is half the mass times velocity squared and is a scalar. The two are conserved under different conditions, since momentum is conserved in every collision whereas kinetic energy is conserved only in elastic ones and is partly converted to heat and deformation in inelastic ones. Impulse is the change in momentum produced by a force acting over an interval. Inertia is the resistance to any change in motion, whereas momentum is the quantity of motion actually possessed.
Hindi Meaning
संवेग (samveg); आवेग (āveg) for impulse.
Common Questions
- Is momentum conserved in all collisions?
- Yes, in the absence of external forces momentum is conserved in every collision, while kinetic energy is conserved only in elastic collisions.
- Why do airbags and crumple zones reduce injury?
- They extend the time over which the body's momentum changes, and since impulse is force multiplied by time, a longer time means a smaller force.
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