Physics Q&A for Class 12
2 free answers in Physics for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
PhysicsClass 12CBSE
Bullet fires with velocity u; after 24 cm velocity = u/3. Then comes to rest at end of block. Find total length.
Step-1: Find retardation (v² = u² − 2as):(u/3)² = u² − 2a(0.24)u²/9 = u² − 0.48a0.48a = u²(1 − 1/9) = 8u²/9 ⇒ a = 50u²/27Step-2: Additional distance to stop from v = u/3:0 = (u/3)² − 2a·s₂s₂ = (u²/9) / (2 × 50u²/27) = (u²/9) × (27/100u²) = 0.03 m = 3 cmStep-3: Total length:L = 24 cm + 3 cm = 27 cmAnswer: Total length of the block = 27 cm
PhysicsClass 12CBSE
Magnetic Moment of a Current-Carrying Wire Bent into a CircleWire length = 2 m, current = 3.14 A (≈ π A). Find magnetic moment M.
Step-1: Radius of circle:2πr = 2 ⇒ r = 1/π mStep-2: Area:A = πr² = π × (1/π)² = 1/π m²Step 3 — Magnetic moment:M = I × A = π × (1/π) = 1 A·m²Answer: M = 1 A·m²