B. Boiling point of water increases due to high pressure
C. Heat is trapped inside
D. Material conducts heat better
Answer: Option B
Solution (By JKSSB Mock Tests)
Pressure cooker seals steam, increasing internal pressure above atmospheric. Higher pressure raises water's boiling point (above 100°C), allowing food to cook at higher temperature, speeding up chemical reactions. Option A is vague; C and D are secondary effects. Memory tip: 'Higher pressure ⇒ higher boiling point ⇒ faster cooking'. This daily-life physics question tests application of pressure-temperature relationship in liquids, frequently appearing in competitive exams. Always recall that phase change temperatures depend on pressure (e.g., water boils below 100°C on mountains).
Explanation:
54 km/h = 15 m/s. u=15, v=0, t=5. a = (0-15)/5 = -3 m/s². s = ut+½at² = 15×5 + ½×(-3)×25 = 75 - 37.5 = 37.5 m. Or s = (u+v)/2 × t = 7.5×5 = 37.5 m.
Explanation:
When the stone is moving in a circle, its velocity vector is always tangential to the circle. The string provides the necessary centripetal force directed towards the center. When the string breaks, this inward force ceases to exist. Due to inertia of direction (Newton's First Law), the stone continues to move along the tangent at the point where the string broke.
Explanation:
Average speed = 2v₁v₂/(v₁+v₂) = 2×40×60/(40+60) = 4800/100 = 48 km/h. Not arithmetic mean (50). For equal distances, harmonic mean of speeds. If times equal, arithmetic mean applies.
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