1. Motion (Gati)
Simple Concept: Jab koi vastu samay ke saath apni sthiti (position) badalti hai.
Key Terms:
Distance vs Displacement: Distance raste ki lambai hai, jabki Displacement do points ke beech ki sabse choti duri hai.
Speed & Velocity: Speed = Distance/Time. Velocity = Displacement/Time.
Acceleration ($a$): Velocity mein badlav ki dar. $a = \frac{v - u}{t}$.
Equations of Motion:
$v = u + at$
$s = ut + \frac{1}{2}at^2$
$v^2 = u^2 + 2as$
2. Force and Laws of Motion (Bal aur Gati ke Niyam)
Simple Concept: Force ek push ya pull hai jo kisi vastu ki speed ya direction badal sakta hai.
Newton’s Laws:
1st Law (Inertia): Vastu apni sthiti nahi badlegi jab tak bahari bal na lage.
2nd Law: $F = ma$ (Force = Mass $\times$ Acceleration).
3rd Law: Har action ka equal aur opposite reaction hota hai.
Momentum ($p$): $p = m \times v$.
3. Gravitation (Gurutvakarshan)
Universal Law of Gravitation: Brahmand mein har vastu dusri vastu ko kheenchni hai. $F = G \frac{M \times m}{d^2}$.
Free Fall: Jab koi cheez sirf gravity ki wajah se niche girti hai. Acceleration due to gravity ($g$) = 9.8 m/s².
Mass vs Weight: Mass kabhi nahi badalta, lekin Weight ($W = m \times g$) jagah ke hisab se badal sakta hai (Moon par weight 1/6th ho jata hai).
4. Work and Energy (Kaarya aur Urja)
Work ($W$): Jab force lagane se vastu move kare. $W = F \times s$. Unit: Joule.
Energy: Kaam karne ki kshamta.
Kinetic Energy ($E_k$): Gati ke karan urja. $E_k = \frac{1}{2}mv^2$.
Potential Energy ($E_p$): Height ke karan urja. $E_p = mgh$.
Power ($P$): Kaam karne ki raftar. $P = W / t$. Unit: Watt.
5. Sound (Dhwani)
Production: Sound vibrations se paida hoti hai.
Medium: Sound ko chalne ke liye Medium (Solid, Liquid, Gas) chahiye. Ye vacuum mein nahi chal sakti.
Characteristics:
Pitch: Frequency par nirbhar karti hai.
Loudness: Amplitude par nirbhar karti hai.
Echo: Sound ka takra kar wapas aana. Minimum distance 17.2m honi chahiye.