Noesis
1.5.4 · D5 · HinglishRotational Mechanics

Question bank — Torque τ = r × F — definition, physical meaning

1,661 words8 min read↑ Read in English

1.5.4 · D5 · Physics › Rotational Mechanics › Torque τ = r × F — definition, physical meaning

Shuru karne se pehle, teen words jo tumhare paas pakke hone chahiye taaki har reveal clean padhe:

  • Pivot / axis — wo fixed line jiske around body rotate karti; hamesha yahan se draw hota hai.
  • Line of action — wo infinite straight line jo force arrow ko dono taraf extend karne se milti hai.
  • ==Moment arm == — pivot se us line of action tak ki sabse choti (perpendicular) distance; ke barabar hoti hai.

Sahi hai ya galat — justify karo

Badi magnitude wali force hamesha zyada torque produce karti hai.
Galat. Torque hai , isliye ek bahut badi force jo seedha pivot ki taraf aimed ho () zero torque deti hai, jabki ek halki sideways push door se kaafi torque de sakti hai.
Agar do forces ki magnitude same ho aur moment arm bhi same ho, to wo same-magnitude torque produce karte hain.
Sahi. sirf moment arm aur force size par depend karta hai, is baat par nahi ki line of action par force kahaan draw ki gayi hai.
Torque aur energy ko add kiya ja sakta hai kyunki dono N·m mein measure hote hain.
Galat. Dono ke dimensions share hain lekin torque ek vector hai aur energy ek scalar; tum kabhi ek twisting axis ko joules ki ek number ke saath add nahi karte.
Pivot par exactly apply ki gayi force zero torque produce karti hai, chahe direction kuch bhi ho.
Sahi. Wahan hai, isliye har ke liye — jo point tum seedha push kar rahe ho, woh twist nahi hota.
Kisi force ko uski apni line of action ke along slide karna fixed pivot ke baare mein torque change kar deta hai.
Galat. Moment arm (pivot se us line tak ki perpendicular distance) unchanged rehta hai, isliye fixed rehta hai — yahi wajah hai ki line of action matter karti hai, contact point nahi.
Force ki direction reverse karna () rotation ka sense flip kar deta hai.
Sahi. , isliye torque vector flip ho jaata hai, anticlockwise clockwise mein badal jaata hai.
Sirf distance ko double karna (same force, same angle) torque ko double kar deta hai.
Sahi. mein linear hai, isliye double lever length double twist deta hai — door-handle rule.
Torque hamesha us force ke perpendicular hota hai jo use create karta hai.
Sahi. cross product ki definition se dono aur ke perpendicular hota hai, isliye yeh kabhi force ki direction mein point nahi kar sakta.
Agar aur dono -plane mein hain, to torque ke along point karta hai.
Sahi. Do in-plane vectors ka cross product us plane ke normal hota hai, isliye ek planar problem hamesha out-of-plane axis ke along torque deta hai.
Ek radial (inward ya outward) pull kabhi bhi pivot ke around object ko spin nahi kar sakta.
Sahi. Ek radial force ke parallel/antiparallel hoti hai ( ya ), aur hota hai, isliye yeh axis ki taraf sirf stretch ya compress karti hai, kabhi circulate nahi karti.

Error dhundho

"Wrench ko uski length se par push karo, isliye use karo."
Error: twisting part woh component hai jo ke perpendicular hai, jo hai, nahi. wali instinct kisi axis par project karne se aati hai; torque ko sideways leftover chahiye.
" jahan force apply hoti hai wahan se pivot tak jaata hai."
Error: direction ulti hai. pivot par start hoti hai aur application point ki taraf point karti hai; ise reverse karne se torque ka sign flip ho jaata hai.
"Torque zero hai, isliye object equilibrium mein hai."
Error: zero net torque ka matlab hai koi angular acceleration nahi, lekin object constant rate par spin karta reh sakta hai, aur uske center of mass par net force bhi ho sakti hai — dekho Equilibrium of Rigid Bodies.
"Force badi hai, aur object tab bhi rotate nahi hua, isliye torque mein koi flaw hoga."
Error: koi flaw nahi — agar extra force ke along aimed hai, to uska zero torque contribute karta hai. Formula ko blame karne se pehle hamesha moment arm check karo.
", aur maine ko horizontal se angle measure kiya."
Error: woh angle hai jo aur ke beech hai, force aur kisi fixed axis ke beech nahi. Galat reference angle use karne se galat milta hai.
"Do forces aur N·m ke torques dete hain, isliye total twisting N·m hai."
Error: signs opposite senses encode karte hain, isliye wo cancel hokar net torque dete hain; tum signed values add karte ho, magnitudes nahi.

Kyun wale questions

Torque aur ke ordinary product ki jagah cross product kyun use karta hai?
Kyunki twist position aur force ke beech ke angle par depend karta hai aur ek directed rotation axis produce karta hai; Cross Product (Vector Algebra) par based cross product exactly perpendicular part aur right-hand rule se axis capture karta hai.
Torque maximum kyun hota hai jab force ke perpendicular ho?
par force ka saara hissa "sideways" (tangential) hota hai, isliye aur har newton circulation mein contribute karta hai; koi bhi tilt force ka ek hissa radially waste kar deta hai.
Ek hi torque ko "" aur "" dono tarike se kyun padha ja sakta hai?
Dono sirf ko alag tarike se group karna hai: ko ke saath group karo to sideways force milti hai, ya ke saath group karo to moment arm milta hai — multiplication ko fark nahi padta ki factor kahan hai.
Ek hi physical push door ko handle par easily kyun open karti hai lekin hinge ke paas mushkil se?
Moment arm (hinge line se tumhare push tak ki distance) handle par badi hoti hai aur hinge ke paas tiny hoti hai, aur directly iske saath scale karta hai.
Torque Newton's law mein force ka rotational partner kyun hai?
Jaise force linear acceleration set karti hai, net torque angular acceleration set karta hai ke through — dekho Newton's Second Law for Rotation aur Moment of Inertia.
Torque plain momentum ki jagah angular momentum se relate kyun karta hai?
Torque Angular Momentum ka time rate of change hai (), "force momentum ka rate of change hai" ka rotational echo.

Edge cases

Agar force pivot se guzarne wali line ke exactly along act kare to torque kya hoga?
Zero, kyunki se ya aur milta hai — force sirf axis ki taraf/se push karti hai.
Pivot ko force ki apni line of action par rakhne par torque kya hoga?
Zero: moment arm hai kyunki line pivot se guzarti hai, isliye force size se independent hai.
Zero magnitude ki force kya torque produce karti hai, chahe position kuch bhi ho?
Zero, kyunki mein ek factor hai — koi force nahi, koi twist nahi, kisi bhi distance ya angle par.
Agar aur exactly same direction mein point karein, to torque kya hoga?
Zero — jo parallelogram wo span karte hain woh zero area ki flat line mein collapse ho jaata hai, isliye .
Jab fixed aur par se hote hue tak sweep kare, to kaise behave karta hai?
Yeh se rise karta hai, par maximum tak pahunchta hai, phir par wapas par aa jaata hai, ki shape trace karta hai — perpendicular ke baare mein symmetric.
Kisi pivot ke baare mein torque pivot ki choice par depend karta hai?
Haan — pivot ko move karne se (aur ) change hota hai, isliye same force generally alag pivots ke baare mein alag torques deti hai; sirf ek couple (equal, opposite, offset forces) pivot se independent torque deta hai.
Agar poori force center of mass par pivot ke through act kare, to kya gravity us pivot ke baare mein kabhi torque create kar sakti hai?
Nahi — agar pivot center of gravity ke saath coincide kare, to weight ki line of action pivot se guzarti hai, hota hai, aur gravitational torque vanish ho jaata hai; dekho Center of Mass & Gravity.