भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – इन्जिनियरिङ प्रवेश
Physics · Engineering Entrance – Mathematics, Physics, Chemistry & English · १,३९८ प्रश्न
१,३९८ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान (Physics): प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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Two wires of the same material have lengths in the ratio 1 : 2 and radii in the ratio 2 : 1. Under the same stretching force, their extensions are in the ratio:
सही उत्तर: घ) 1 : 8
ΔL = FL/(πr²Y) ∝ L/r²: (1/4) : (2/1) = 1 : 8.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Kepler's second law (equal areas in equal times) is a consequence of the conservation of:
सही उत्तर: क) angular momentum
Gravity is a central force, so it exerts no torque about the Sun and the planet's angular momentum is conserved, giving constant areal velocity.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The gravitational potential energy of two point masses M and m separated by distance r is:
सही उत्तर: ख) −GMm/r
Taking zero at infinity, U = −GMm/r; it is negative because gravity is attractive.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A spring of force constant k is cut into two equal halves and the same mass is attached to one half. The frequency of oscillation becomes:
सही उत्तर: ग) √2 times
Each half has force constant 2k, and f ∝ √k, so f increases by √2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A disc rotating freely about its axis has an identical non-rotating disc gently placed on it coaxially, and they rotate together. The fraction of the initial rotational kinetic energy lost is:
सही उत्तर: घ) 1/2
Angular momentum Iω = 2Iω′ gives ω′ = ω/2; final KE = ½(2I)(ω/2)² = ¼Iω², half of the initial ½Iω².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A planet has the same mean density as the Earth but twice its radius. The acceleration due to gravity on its surface is:
सही उत्तर: क) twice that on the Earth
g = GM/R² = (4/3)πGρR, so for the same density g ∝ R; doubling R doubles g.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The acceleration due to gravity at a depth R/2 below the Earth's surface (R = radius of Earth) is:
सही उत्तर: घ) g/2
g_d = g(1 − d/R) = g(1 − 1/2) = g/2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A bullet of mass m moving horizontally with speed v embeds itself in a block of mass M hanging from a string. The height to which the block rises is:
सही उत्तर: ख) (mv/(m + M))²/(2g)
Momentum conservation gives V = mv/(m + M), and then ½V² = gh, so h = V²/(2g).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The angular speed of the minute hand of a clock is:
सही उत्तर: ख) π/1800 rad/s
The minute hand turns 2π rad in 3600 s, so ω = 2π/3600 = π/1800 rad/s.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The maximum safe speed of a vehicle on an unbanked circular road of radius r with coefficient of friction μ is:
सही उत्तर: घ) √(μrg)
Friction provides the centripetal force: mv²/r ≤ μmg, so v_max = √(μrg).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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