1.1.19 · D1 · Physics › Measurement, Vectors & Kinematics › Projectile motion — horizontal - vertical independence, full
Ek phénka hua ball asliyat mein do alag motions ek saath kar raha hota hai: ek side mein steady speed se khisak raha hai, aur seedha neeche gravity ke under gir raha hai. Parent derivation padhne ke liye bas tumhe un muthi bhar arrows, letters, aur slicing tools ko pehchanna hai jo woh use karta hai — yeh page unhe ek-ek karke, bilkul zero se, jis order mein pehle aate hain us hisaab se banata hai.
Yeh page ek toolbox unpacking hai. Parent note (Projectile motion — horizontal - vertical independence, full derivation ) mein F , u cos θ , a y = − g , aur ∫ v d t jaise symbols aise use hote hain jaise tumhe pehle se pata ho. Yahan hum har ek ko earn karte hain, build-order mein, ek picture ke saath.
Definition Cheezein kahan hain
Yeh batane ke liye ki ball kahan hai, humein ek starting corner aur do directions chahiye jahan se measure karein.
==Origin O == woh fixed point hai jahan se hum launch karte hain — "distance zero, height zero."
==x == batata hai ki ball O se kitna sidewise (daayein taraf) gayi hai.
==y == batata hai ki ball O se kitna upar hai.
Figure dekho: O bottom-left corner hai. Dot par baitha hua ball do numbers se describe hota hai — x daayein chalo, phir y upar. Woh do numbers hi uski position hain.
Intuition Do alag numbers kyun?
Kyunki poora topic is baat ke baare mein hai ki sideways story aur up-down story independent hain. x aur y ko alag letters rakhna hi humein ek mushkil problem ki jagah do aasaan problems solve karne deta hai. General machinery ke liye dekho Vectors — Resolving into Components .
t
==t == launch ke baad ke seconds ka number hai. t = 0 par ball O par hai; jaise-jaise t badhta hai ball apne arc par move karta hai.
Intuition Time hero kyun hai
Sideways position x aur height y dono t par depend karte hain. Woh kabhi seedhe ek doosre se baat nahin karte — unka ek hi shared cheez hai, yeh same clock. Agar tumhe t pata hai, to tumhe x aur y dono pata hain. Yeh ek shared clock hi poori wajah hai ki independence kaam karti hai.
Hum x ( t ) aur y ( t ) likhte hain — padho "x at time t " — yeh emphasize karne ke liye ki position time ki ek function hai: mujhe t do, main tumhe position wapas dunga.
v , speed u
Velocity jawab deta hai: "ball kis taraf ja raha hai, aur kitni tez?" Hum ise ==arrow v == ki tarah draw karte hain — chhota arrow-hat matlab "yeh ek directioned quantity (ek vector) hai, sirf plain number nahin."
Arrow ki length speed hai. Launch speed ko ==u == kehte hain.
Direction woh hai jis taraf woh point karta hai.
Ek vector ek physical arrow hai jo tum ruler se draw kar sakte ho. Speed u batata hai use kitna lamba banana hai; direction batata hai use kahan aim karna hai.
θ
==θ (Greek "theta") launch arrow aur ground ke beech ka angle== (horizontal) hai. θ = 0 matlab bilkul flat fire kiya; θ = 9 0 ∘ matlab seedha upar fire kiya.
Agla figure dekho: amber arrow length u ki launch velocity hai, ground line se θ upar tilt kiya hua.
Yeh single most important tool hai jo parent assume karta hai. Hum ise dheere-dheere banate hain.
Definition Velocity ka right triangle
Launch arrow ki tip ko seedha neeche ground par drop karo, aur O se us foot tak ek flat line draw karo. Ab tumhare paas ek right-angled triangle hai:
slanted side (hypotenuse) ki length u hai,
flat bottom side sideways part hai, u x ,
upright side upar wala part hai, u y .
Usi figure mein cyan dashed lines yeh do sides dikhati hain. Sideways shadow u x hai; vertical shadow u y hai.
Definition IS triangle par
cos aur sin
Angle θ ke liye ek right triangle mein:
cos θ = hypotenuse adjacent = u u x , sin θ = hypotenuse opposite = u u y
"Adjacent" = woh side jo angle ko touch karti hai (flat bottom). "Opposite" = woh side jo angle ke saamne hai (upright). Rearrange karo:
u x = u cos θ u y = u sin θ
Intuition Cosine aur sine hi kyun, kuch aur nahin?
Humein ek aisa rule chahiye jo "length u ka ek arrow θ se tilt kiya hua" ko "kitna sideways point karta hai" aur "kitna upar point karta hai" mein convert kare. Cosine aur sine literally un dono fractions ke roop mein define hain hypotenuse ke. Woh exactly woh tools hain jo ek arrow ko uske shadows mein split karte hain — koi aur function "fraction along each axis" nahin measure karta.
Common mistake "cos hamesha
x ke saath jaata hai — main yeh yaad kar lunga."
Kyun safe lagta hai: jab θ horizontal se measure hota hai tab kaam karta hai.
Fix: cos us side ke saath jaata hai jo angle ke adjacent hai. Agar koi problem angle ko vertical se measure kare, to cos aur sin swap ho jaate hain. Hamesha triangle dobara draw karo. Aur zyada Vectors — Resolving into Components mein.
Worked example Extreme cases check karo
θ = 0 ∘ : cos 0 = 1 , sin 0 = 0 → u x = u , u y = 0 . Sab sideways, kuch upar nahin — flat throw. ✓
θ = 9 0 ∘ : cos 9 0 ∘ = 0 , sin 9 0 ∘ = 1 → u x = 0 , u y = u . Seedha upar, kuch sideways nahin. ✓
θ = 4 5 ∘ : cos 4 5 ∘ = sin 4 5 ∘ ≈ 0.707 → equal shares. ✓
a
Acceleration hai velocity khud kitni tez change ho rahi hai har second. Units: metres per second, per second (m/s 2 ). Zero acceleration matlab "velocity frozen." Positive a matlab chosen positive direction mein speed up ho raha hai.
g aur minus sign
==g ≈ 9.8 m/s 2 == (parent 10 use karta hai clean arithmetic ke liye) yeh hai ki gravity Earth ke paas kisi bhi cheez ko kitna accelerate karti hai. Kyunki humne upar ko positive y choose kiya hai, aur gravity neeche kheenchti hai, vertical acceleration hai
a y = − g
Minus sign extra physics nahin hai — yeh bookkeeping hai: neeche hamare y -axis par negative direction hai. Dekho Free Fall and g .
Dono directions yahan perfectly split hote hain:
a x = 0 ( koi sideways push nahin ) , a y = − g ( gravity, downward ) .
Definition Force as a vector
==Force F == ek push ya pull hai — yeh bhi ek arrow hai. Mass m par gravity ki force F = ( 0 , − m g ) hai: sideways zero , m g neeche.
Intuition Yeh independence KYUN DETA hai
Dekho a x ki equation mein koi y nahin hai, aur a y ki equation mein koi x nahin hai. Do axes decoupled hain — ek solve karne ke liye doosre ki zaroorat nahin. Yeh decoupling, yahan se janam leti hai, poore topic ka engine hai.
Parent likhta hai a = d t d v aur x = ∫ v d t . Yahan woh squiggles ka matlab hai, zero se.
d t d v
d t d v ka matlab hai "time ke chhote slice par v kitni tez change hoti hai." Yeh bas acceleration as a rate likha hua hai. d t d v x = 0 kehna matlab "v x kabhi nahin badalti" — ek flat, constant sideways speed.
∫ v d t
∫ sign matlab "add up karo sab chhote steps." Agar tum speed v se ek tiny time slice ke liye move karo, to tum v d t distance cover karte ho; launch se time t tak woh saare slices add karna total distance deta hai. Isliye x = ∫ v x d t . Constant v x = u cos θ ke liye yeh bas speed × time = u cos θ t hai. Dekho Calculus — Integration .
Intuition Integration SAHI tool kyun hai
Humein acceleration diya gaya hai aur position chahiye. Acceleration velocity ka rate of change hai; velocity position ka rate of change hai. Integration exactly "undo" hai ek rate ka — yeh seedhi upar ladder par chadhta hai: acceleration → velocity → position. Parent derivation mein Step 1 aur Step 2 ka yahi poora kaam hai. Aur kyunki a y = − g mein koi mass nahin hai, Free Fall and g kisi bhi projectile par apply hota hai chahe weight kuch bhi ho.
Agar constant acceleration comfortable lage ready-made formulas ke roop mein (no calculus), algebraic route v = u + a t , s = u t + 2 1 a t 2 1-D Kinematics — Equations of Motion mein hai — yeh wahi result hai jo integration produce karta hai.
tan θ
==tan θ = cos θ sin θ = u x u y == launch ki steepness (rise-over-run) hai. Trajectory equation y = x tan θ − … mein, tan θ term woh straight climb hai jo ball without gravity follow karta; − 2 u 2 cos 2 θ g x 2 term gravity hai jo use neeche bend karti hai.
Parabola woh curve hai jo y = a x − b x 2 form ki equation se milti hai (ek squared term use neeche kheenchta hai). Figure mein do pieces add hote dikhte hain: ek rising straight line minus growing downward pull barabar familiar arc.
Position x y and origin O
Parametric equations x of t and y of t
Velocity arrow and speed u
Split into components u cos and u sin
Newton second law per axis
a x equals 0 and a y equals minus g
Trajectory range height time of flight
Ise top-to-bottom padho: left/top par raw ideas parametric equations x ( t ) , y ( t ) ko feed karte hain, aur woh badle mein har woh result dete hain jo parent box karta hai.
Daayein side cover karo aur khud test karo — jab har ek instant ho tab tum full derivation ke liye ready ho.
x aur y kya measure karte hain, aur kahan se?Sideways distance aur height, dono origin O se.
Horizontal aur vertical motions mein ek shared cheez kya hai? Clock — same time t .
Arrow-hat ka matlab kya hai? Quantity ek vector hai: uski direction hai, sirf size nahin.
θ kahan se measure hota hai?Horizontal ground line se.
u x aur u y ko u aur θ mein likho.u x = u cos θ , u y = u sin θ .
Horizontal part ke liye cosine kyun? Cosine adjacent-over-hypotenuse hai; horizontal side θ ke adjacent hai.
a x kya hai aur kyun?0 , kyunki koi horizontal force nahin hai.
a y = − g kyun hai (minus kyun)?Upar positive hai; gravity neeche point karti hai, isliye us axis par uska acceleration negative hai.
Kya a y mein mass aata hai? Nahin — mass − m g = m a y mein cancel ho jaata hai, isliye saare projectiles ek jaise girte hain.
a = d t d v words mein kya kehta hai?Acceleration woh rate hai jis par velocity per unit time change hoti hai.
∫ v d t kya karta hai?Saare chhote v d t steps add karta hai total displacement dene ke liye (velocity → position).
Path parabola kyun hai? Height equation ki form y = a x − b x 2 hai, x mein quadratic.
tan θ geometrically kya hai?Launch ki steepness (rise over run), u y / u x .