A person cannot see distant objects clearly. This defect is called
A. Cataract
B. Myopia
C. Presbyopia
D. Hypermetropia
Answer: Option B
Solution (By JKSSB Mock Tests)
Myopia (nearsightedness): image formed before retina, corrected with concave lens. Hypermetropia: cannot see near objects. Presbyopia age-related. Cataract lens opacity.
Explanation:
72 km/h = 72 × (5/18) = 20 m/s. Initial velocity u = 20 m/s, final v = 0, t = 10 s. Using v = u + at => 0 = 20 + a×10 => a = -2 m/s², so deceleration magnitude is 2 m/s². Conversion factor 5/18 is essential: multiply km/h by 5/18 to get m/s.
Explanation:
Total time of flight T = 2u/g => u = gT/2 = 10×6/2 = 30 m/s. Max height H = u²/(2g) = 900/20 = 45 m. Alternatively, time to max height = 3 s, H = ½g t² = ½×10×9 = 45 m.
Explanation:
Heat for phase change Q = m·L_f, where L_f is latent heat of fusion. Thus Q = 2 kg × 336 kJ/kg = 672 kJ. This direct application tests calorimetry fundamentals. Memory aid: 'Latent heat: Q = mL; no temperature change during phase transition'. Competitive exams frequently test such calculations with standard values. Always ensure units match (kg and kJ/kg here); convert if necessary. This problem assesses basic formula application skills essential for thermodynamics sections.
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