A car accelerates uniformly from 18 km/h to 36 km/h in 5 seconds. The distance covered is
A. 45 m
B. 75 m
C. 54 m
D. 37.5 m
Answer: Option D
Solution (By JKSSB Mock Tests)
Convert speeds: 18 km/h = 5 m/s, 36 km/h = 10 m/s. Using v = u + at => a = (10-5)/5 = 1 m/s². Distance s = ut + ½at² = 5×5 + ½×1×25 = 25 + 12.5 = 37.5 m. Also using average velocity: (5+10)/2 × 5 = 7.5×5 = 37.5 m. Answer A.
Explanation:
Law of reflection: angle of incidence = angle of reflection, both measured from normal. So 30°. If angle with mirror is given, convert to normal. Always equal for smooth surfaces.
Explanation:
The time period of a simple pendulum is given by T = 2π√(L/g), where L is the length of the string and g is acceleration due to gravity. The time period is directly proportional to the square root of the length (T ∝ √L). If L becomes 4L, the new time period T' = √4 = 2 times the original. It doubles.
Explanation:
Myopia (nearsightedness) is the inability to see distant objects clearly, with far point less than infinity. Here, far point is 2 m. Corrected using concave lens. Hypermetropia (farsightedness) affects near vision; presbyopia is age-related loss of accommodation; astigmatism involves uneven corneal curvature. Memory aid: 'Myopia = near-sighted; far point reduced'. This application question tests knowledge of vision defects and corrections, frequently appearing in competitive exams. Always link symptom (blurred distant vision) to defect (myopia) and correction (diverging lens).
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