The kinetic energy of a body becomes four times its initial value. The new momentum will be:
A. Same as initial
B. Twice the initial
C. Half the initial
D. Four times the initial
Answer: Option B
Solution (By JKSSB Mock Tests)
Kinetic energy KE = p²/(2m), where p is momentum. Thus p = √(2m·KE). If KE becomes 4 times, p_new = √(2m·4KE) = 2√(2m·KE) = 2p_initial. Hence momentum doubles. This relationship shows momentum scales with square root of kinetic energy for constant mass. Memory tip: p ∝ √KE when mass constant. This conceptual link between momentum and kinetic energy is frequently tested in competitive exams to assess depth of understanding beyond rote formula memorization. Always derive relationships when direct formulas aren't recalled.
Explanation:
Archimedes' principle: buoyant force = weight of fluid displaced. This force acts upward. If buoyant force ≥ weight, object floats. Submarines use ballast tanks to change weight, altering buoyancy.
Explanation:
The transformer equation relates voltages to the number of turns: V_secondary / V_primary = N_secondary / N_primary. We have N_p = 50, N_s = 1000, and V_p = 220V. Substituting the values gives V_s / 220 = 1000 / 50. V_s = 220 * 20 = 4400 Volts. This is a step-up transformer, increasing the voltage strictly by a factor of 20.
Explanation:
Acceleration phase: s₁ = ½a t² = ½×2×100 = 100 m, v = a t = 20 m/s. Constant velocity phase: s₂ = v×t = 20×10 = 200 m. Total = 300 m. Motion in two parts.
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