Assertion: Acceleration in SHM is maximum at extremes. Reason: Restoring force ∝ displacement.
A. Both true, R doesn't explain A
B. A false, R true
C. Both true, R explains A
D. A true, R false
Answer: Option C
Solution (By JKSSB Mock Tests)
Assertion true: a = -ω²x, max at max |x|. Reason true: F = -kx (Hooke's law), and F = ma ⇒ a ∝ -x. Reason correctly explains why acceleration peaks at extremes. Memory tip: 'SHM: F ∝ -x ⇒ a ∝ -x'. Assertion-reason testing SHM fundamentals, frequently examined in competitive exams.
Explanation:
Work done is given by W = F * d * cos(theta). In uniform circular motion, the centripetal force is always directed strictly towards the center of the circle, while the instantaneous displacement (velocity vector) is tangential to the circle. The angle (theta) between them is exactly 90 degrees. Since cos(90) = 0, the work done by the centripetal force is always zero.
Explanation:
Electrical resistance (R) is Voltage/Current. Voltage (V) is Work/Charge. Work is [ML^2T^-2] and Charge is [AT]. So, V = [ML^2T^-3A^-1]. Therefore, R = V/A = [ML^2T^-3A^-2]. Memorizing the dimensional formula for resistance is highly recommended for competitive exams.
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