Practice Section
Timed. Tiered. Real exam-style. Easy (Boards) → NEET → JEE Main → JEE Advanced. Start the timer, attempt, reveal answers. No cheating allowed — yourself.
v = u + at = 0 + 3 × 10 = 30 m/s
Use v = u + at. u = 0 (from rest), a = 3 m/s², t = 10 s.
Displacement = 8 − 6 = 2 m east. Net = algebraic sum with direction. Distance = 14 m (total path).
h = ½gt² = ½ × 10 × 9 = 45 m. u = 0, a = g = 10 m/s², t = 3 s. Use s = ut + ½at².
Displacement (with sign). Area above t-axis = positive displacement. Area below = negative displacement. Slope of v-t graph = acceleration.
v² = u² + 2as — contains v, u, a, s but no t. Use this whenever time is absent from the problem.
At max height, v = 0. Use v = u − gt → 0 = 20 − 10t → t = 2 s
Using sₙ = u + a(n−½) with u=0: s₁ = a/2, s₂ = 3a/2, s₃ = 5a/2. Ratio = 1 : 3 : 5 (odd number series). Classic NEET trap.
72 km/h = 20 m/s. v²=u²+2as → 0 = 400+2(a)(40) → a = −400/80 = −5 m/s² → retardation = 5 m/s²
v = −5 (negative direction), a = +3 (positive direction). v and a are in opposite directions → speed decreases. The particle is decelerating even though a is positive.
Relative velocity = 60 + 40 = 100 m/s (approaching). t = d/v_rel = 200/100 = 2 s
a = 2t → variable. Integrate: v = ∫2t dt = t² + C. At t=0, v=0 → C=0. v(3) = 9 m/s. Cannot use v=u+at as a is not constant!
Up = +ve, origin at top. s = −25 m (ground below). s = ut + ½at² → −25 = 20t − 5t² → 5t² − 20t − 25 = 0 → t² − 4t − 5 = 0 → (t−5)(t+1) = 0 → t = 5 s
sₙ = u + a(n − ½) = 0 + 4(5 − ½) = 4 × 4.5 = 18 m. This is distance in the 5th second specifically, not total 5 seconds.
a = v·dv/dx. v = 3x²+2, dv/dx = 6x. At x=1: v = 5, dv/dx = 6. a = 5 × 6 = 30 m/s²
a = −kv. x = ∫v dv/a = ∫v dv/(−kv) = −(1/k)∫dv = −(v−v₀)/k. When v = v₀/e: x = (v₀ − v₀/e)/k = v₀(1−1/e)/k = 4(1−1/e)/2 = 2(1−1/e) ≈ 1.26 m. Exact: 2(1−1/e) m
Straight line → constant slope → constant velocity (A correct). Zero curvature → zero acceleration (C correct). Negative slope = negative velocity, which still has positive speed magnitude (D wrong). Not decelerating since a = 0 (B wrong). Correct: A and C