Mehira Education ←Science Ch 1 · Units, Motion aur Force 🔥 1 din ⚡ 0 XP Lv 1 0%
Mehira Education logoMEHIRA EDUCATIONSeekho · Samjho · Aage Badho General Science · Chapter 01 · Physics

Units, Motion aur Force

SI units se Newton's laws tak — formula kam, samajh zyada. Saamne wali balls ko kheencho aur khud dekho ki momentum kaise travel karta hai.

⏱ 18 min🧪 5 labs🃏 20 cards✍️ 14 MCQs⚡ +230 XP
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Live Lab · Momentum

Ball ko kheencho aur chhodo — jitni balls chhodoge, doosri side se utni hi uchhlengi.

p = mv

Newton's cradle — conservation of momentum aur energy

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3 labs chalao

Speed, temperature, sorter

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Flashcards

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Poora quiz, 10 sahi

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01 — NOTES

Poore notes, ek-ek karke

Har lesson ke saath ek chhota lab hai — padho, phir khud chala ke dekho.

00

Introduction — ye chapter kyun?

Dosto, General Science ki shuruaat Physics ke sabse basic topic se — cheezon ko measure karna aur cheezein move kaise karti hain. Is chapter ke chaar bade parts hain: SI units, scalar aur vector quantities, motion aur Newton's laws of motion.

CET Group D mein Science ke questions Class 10 level ke hote hain — lambi calculation nahi, seedhe concepts. Jaise: "Light year kis quantity ki unit hai?", "Rocket kis law par kaam karta hai?", "72 km/h kitne m/s?" Ye sab isi ek chapter se aate hain.

Aur Haryana connection bhi hai — Neeraj Chopra (Khandra, Panipat) ka javelin aur Bhiwani ke boxers ke gloves, dono ke peeche isi chapter ki Physics hai.

01

Physical quantities aur SI units ★ exam favourite

Jis cheez ko measure kiya ja sake, use physical quantity kehte hain. Poori duniya ek hi system use karti hai — SI system. Isme 7 base units hain, baaki saari units (derived units) inhi se banti hain. Har tile par tap karo.

mMummy
metreLength
kgKi
kilogramMass
sSaari
secondTime
AAlmari
ampereElectric current
KKholo
kelvinTemperature
molMile
moleAmount of substance
cdChocolate
candelaLuminous intensity

Mummy Ki Saari Almari Kholo, Mile Chocolate

Derived quantitySI unit
Forcenewton (N) = kg·m/s²
Work / Energyjoule (J)
Powerwatt (W)
Pressurepascal (Pa)
Frequencyhertz (Hz)
Charge / Potential / Resistancecoulomb (C) / volt (V) / ohm (Ω)
★ Special units — exam ka favourite
  • Light year = distance ki unit hai (time ki NAHI!) ≈ 9.46 × 1015 m
  • Astronomical Unit (AU) = Earth aur Sun ke beech ki average distance ≈ 1.5 × 1011 m (15 crore km)
  • Parsec = 3.26 light years — sabse badi distance ki unit
  • Nautical mile = 1852 m — ships aur aircraft ki distance · Knot = ship ki speed
  • Angstrom (Å) = 10−10 m · Micron = 10−6 m · Fermi = 10−15 m (nucleus jitni chhoti distance)
  • 1 Horse Power (HP) ≈ 746 watt · 1 kWh ("1 unit" bijli) = 3.6 × 106 joule

Temperature scales: K = °C + 273 · °F = (9/5 × °C) + 32 · normal body temperature 37 °C = 98.6 °F · paani 0 °C (32 °F) par freeze hota hai aur 100 °C (212 °F) par boil (sea level par).

Lab 1

Thermometer — slider kheencho

−40 dhoondo!
Celsius25°C
Fahrenheit77°F
Kelvin298K
★ −40 par °C = °F — exam ka pakka question! 37 °C = 98.6 °F — body temperature
02

Scalar aur Vector quantities ★

Scalar mein sirf magnitude hota hai. Vector mein magnitude + direction dono.

ScalarVector
MatlabSirf magnitudeMagnitude + direction
ExamplesMass, distance, speed, time, work, energy, temperature, pressure, electric currentDisplacement, velocity, acceleration, force, momentum, weight
⚠ Do traps Electric current ki direction hoti hai, phir bhi ye scalar hai (vector addition ke rules follow nahi karti). Mass scalar hai (kg) · Weight vector hai (newton) — kyunki weight ek force hai jo neeche ki direction mein lagta hai.
Lab 2

Sort karo — Scalar ya Vector?

10 quantities
Scalar sirf magnitude
Vector magnitude + direction

Upar se koi quantity chuno, phir sahi box par tap karo.

03

Motion ★

TermMatlabSI unit
DistanceTotal path jo cover kiyam
DisplacementStarting point se final point tak ki seedhi distance (direction ke saath)m
SpeedDistance ÷ timem/s
VelocityDisplacement ÷ timem/s
AccelerationVelocity mein change ÷ time (kam ho to retardation)m/s²
  • Circular track ka ek poora round: distance = circumference, par displacement = 0
  • Uniform circular motion — speed same rehti hai, par direction lagatar badalti hai → velocity badalti hai → ye accelerated motion hai
  • Earth par g ≈ 9.8 m/s² — hawa na ho (vacuum) to feather aur coin ek saath girenge
v = u + ats = ut + ½at²v² = u² + 2as
Lab 3

Speed converter — km/h se m/s

× 5/18
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km/h72km/h
m/s20m/s
Calculation72 × 5/18 = 20

Ulta chahiye? m/s → km/h: × 18/5. 36 km/h = 10 m/s · 90 km/h = 25 m/s.

04

Newton's laws of motion ★ sabse zyada questions

LAW 1

Law of Inertia

"AALSI"

Har object apni state mein rehna chahta hai — rest mein hai to rest mein, motion mein hai to motion mein — jab tak koi external force na lage. Bus achanak chale → passengers peeche girte · achanak ruke → aage · carpet jhaadne par dust nikalna · tree hilane par fruits girna.

LAW 2

F = m × a

"ZOR"
m2 kgF6 Na3 m/s²

Force = mass × acceleration. Force = rate of change of momentum. Heavy gaadi ko push karne mein zyada force lagta hai. Momentum p = mv (kg·m/s).

LAW 3

Action–Reaction

"BADLA"

Har action ka equal aur opposite reaction hota hai — dono alag-alag objects par lagte hain. Rocket · gun ka recoil · swimming · walking · boat se kinare par jump karna.

🥊 Impulse — Bhiwani ke boxers ki Physics Impulse = force × time = change in momentum. Momentum ka change utna hi rahe aur time badha do to force kam lagta hai:
  • Cricketer catch lete waqt haath peeche kheenchta hai
  • Boxing gloves aur padding — punch ka time badhakar injury kam (Bhiwani = "Mini Cuba")
  • Car ke airbags, high jump ke liye sand/mattress
  • Mass hi inertia ka measure hai — heavy cheez ko rokna ya chalana mushkil
  • Conservation of momentum — external force na ho to total momentum same rehta hai → gun ka recoil, rocket, aur upar wala Newton's cradle
05

Friction

  • Order: Static > Sliding > Rolling — rolling friction sabse kam
  • Isi liye ball bearings aur wheels · friction kam karne ke liye oil/grease (lubricants)
  • Friction zaroori bhi hai — iske bina hum chal nahi sakte, tyres ke treads grip badhate hain
Lab 4

Friction race — same push, kaun aage?

Static — hila hi nahi
Sliding — ghisatta
Rolling — ludhakta
06

Centripetal force & projectile motion Haryana wala question

🎯 Neeraj Chopra ka javelin — projectile motion Air resistance na ho (ideal case) to koi object 45° par throw karne se sabse door jaata hai. Real life mein air ki wajah se javelin thoda kam angle par throw kiya jata hai. Neeraj Chopra (Khandra village, Panipat) ne Tokyo Olympics 2020 mein 87.58 m throw ke saath gold jeeta.
  • Centripetal force — circle mein ghoomti cheez ko centre ki taraf kheenchta hai
  • Centrifugal effect ke uses — cream separator (doodh se cream), washing machine ka dryer
  • Turn par road ko bahar ki side se ooncha (banking of roads) banaya jata hai
02 — EXAM

Exam mein kya poochha jata hai

CET mein isi chapter se yahi 5 patterns aate hain.

TYPE 1
"Iski SI unit kya hai?"

Sabse zyada aane wala. Force = newton · Energy = joule · Power = watt · Pressure = pascal · Luminous intensity = candela. Dono tables pakki kar lo.

TYPE 2
"Light year / Parsec kis ki unit?"

Light year, parsec aur nautical mile — teeno distance ki units. Knot speed ki. Horse power power ki. kWh energy ki.

TYPE 3
"Kaunsi vector quantity hai?"

Options mein speed, mass, work ke saath ek vector (displacement, velocity, force, momentum) chhupa hota hai. Current aur pressure ka trap yaad rakho.

TYPE 4
"Ye kaunse law ka example?"

Bus ka jhatka = first law (inertia) · rocket, recoil, swimming = third law · catch lete waqt haath kheenchna = impulse / second law.

TYPE 5
Chhoti calculation

km/h ↔ m/s convert karna, ya °C ↔ °F / K. Formula yaad ho to 10 second ka question.

03 — TRICKS

Yaad rakhne ki desi tricks

Ratta nahi — connect karke yaad karo.

TRICK 1 · 7 BASE UNITS
Mummy Ki Saari Almari Kholo, Mile Chocolate

Metre · Kilogram · Second · Ampere · Kelvin · Mole · Candela. Almari kholte hi chocolate — 7 ke 7 yaad.

TRICK 2 · NEWTON'S LAWS
Aalsi – Zor – Badla

1 = Aalsi (inertia — jaisa hai waisa rehna chahta) · 2 = Zor (F = ma — force lagao, acceleration pao) · 3 = Badla (action ka equal aur opposite reaction).

TRICK 3 · LIGHT YEAR
"Delhi 2 ghante door hai"

Jaise hum distance ko ghante mein bolte hain, waise hi light year mein "year" hai par ye measure karta hai distance.

TRICK 4 · km/h ↔ m/s
Bada number 18

km/h se m/s mein number chhota hota hai → × 5/18. m/s se km/h mein bada → × 18/5. 36 km/h = 10 m/s, 90 km/h = 25 m/s.

TRICK 5 · FRICTION
Khada > Ghisatta > Ludhakta

Static cheez ko hilana sabse mushkil, slide karana usse aasan, roll karana sabse aasan. Isliye heavy saman wheels par.

04 — COMMON MISTAKES

Yahan marks katte hain

Har card par galat baat likhi hai. Tap karke sach dekho.

✗ GALAT

"Light year time ki unit hai."

tap karo →
✓ SAHI

Light year = distance. Option mein "time" zaroor hoga — wahi trap hai.

✗ GALAT

"Electric current ki direction hai, to ye vector hai."

tap karo →
✓ SAHI

Direction hone ke bawajood current scalar hai. Pressure bhi scalar.

✗ GALAT

"Mass aur weight ek hi cheez hain."

tap karo →
✓ SAHI

Mass (kg) har jagah same · Weight (N) badalta hai — Moon par 1/6. Beam balance mass measure karta hai, spring balance weight.

✗ GALAT

"Circular motion mein speed same hai, to acceleration nahi."

tap karo →
✓ SAHI

Direction badal rahi hai → velocity badal rahi hai → acceleration hai. Ye pakka trap question hai.

✗ GALAT

"Action aur reaction equal hain, to ek doosre ko cancel kar denge."

tap karo →
✓ SAHI

Dono alag-alag objects par lagte hain, isliye cancel nahi hote. Isi wajah se rocket upar jaata hai.

05 — FLASHCARDS

20 cards, 3D deck

Card par tap karke palto. Next → se agla card, ← Previous se pichhla. Yaad ho gaya to "Yaad hai" dabao — wo card deck se hat jayega. Keyboard: ← → , space (palto), Enter (yaad hai).

06 — REVISION

2-minute revision

Exam se pehle bas ye list. Kuch bhi search karo — "newton", "light", "18"…

7 SI base unitsm, kg, s, A, K, mol, cd
Force / Energy / Powernewton / joule / watt
Pressure / Frequencypascal / hertz
Luminous intensitycandela
Light yearDistance ≈ 9.46 × 10¹⁵ m
Astronomical Unit≈ 1.5 × 10¹¹ m
Parsec3.26 light years
Nautical mile / Knot1852 m / ship ki speed
1 HP / 1 kWh≈ 746 W / 3.6 × 10⁶ J
Kelvin aur °FK = °C + 273 · °F = 9/5 °C + 32
°C = °F−40
Scalar examplesSpeed, mass, work, pressure, current
Vector examplesDisplacement, velocity, force, momentum, weight
km/h → m/s× 5/18
Equations of motionv=u+at · s=ut+½at² · v²=u²+2as
Newton 1 / 2 / 3Inertia / F=ma / Action-reaction
Rocket, recoil, swimmingThird law
ImpulseForce × time = Δ momentum
Friction orderStatic > Sliding > Rolling
Neeraj Chopra (Panipat)Tokyo 2020 gold — 87.58 m
07 — QUIZ

Practice MCQs — game mode

14 exam-style questions, ek-ek karke — koi question nahi aata to Skip karke aage badho. Har sahi answer +5 XP, lagatar sahi par combo. 10+ laao aur quiz mission complete karo.

08 — SUMMARY

Poora chapter, ek paragraph mein

SI system mein 7 base units hain — "Mummy Ki Saari Almari Kholo, Mile Chocolate". Force = newton, energy = joule, power = watt, pressure = pascal; aur light year, AU, parsec teeno distance ki units hain (time ki nahi!). Scalar mein sirf magnitude (speed, mass, current, pressure), vector mein magnitude + direction (displacement, velocity, force, momentum, weight). Circular track ke ek round mein displacement zero, aur circular motion hamesha accelerated. Newton — "Aalsi–Zor–Badla": bus ka jhatka first law, F = ma second, rocket aur recoil third. Catch lete waqt haath kheenchna aur boxing gloves impulse ka kamaal hai. Friction mein rolling sabse kam, aur km/h se m/s ke liye bas × 5/18.

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