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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A uniform rod of length L is pivoted at one end and released from rest in the horizontal position. Its angular velocity as it passes through the vertical position is:
सही उत्तर: ख) √(3g/L)
Loss of PE = Mg(L/2) = ½(ML²/3)ω², which gives ω² = 3g/L.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ring rolls without slipping on a level surface. The fraction of its total kinetic energy that is translational is:
सही उत्तर: ख) 1/2
For a ring I = MR², so rotational KE ½Iω² = ½Mv² equals the translational KE; each is half of the total.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The radius of gyration of a uniform disc of radius R about its own axis (perpendicular to its plane through the centre) is:
सही उत्तर: ख) R/√2
I = ½MR² = MK², so K = R/√2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A solid sphere and a hollow (thin-walled) sphere have the same mass and radius. About a diameter:
सही उत्तर: क) the hollow sphere has the larger moment of inertia
I(hollow) = (2/3)MR² is greater than I(solid) = (2/5)MR², because the hollow sphere's mass lies farther from the axis.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The angular velocity of a flywheel increases uniformly from 10 rad/s to 30 rad/s in 4 s. Its angular acceleration is:
सही उत्तर: ख) 5 rad/s²
α = (ω − ω₀)/t = (30 − 10)/4 = 5 rad/s².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body has moment of inertia I and angular momentum L about a fixed axis. Its rotational kinetic energy is:
सही उत्तर: घ) L²/(2I)
K = ½Iω² and L = Iω, so K = L²/(2I).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The moment of inertia of a uniform solid cylinder of mass M and radius R about its own axis is:
सही उत्तर: ख) MR²/2
Like a disc, a solid cylinder has I = ½MR² about its axis of symmetry.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A bullet loses 1/20 of its velocity in passing through one plank. Assuming the same resistance in each plank, the number of such planks needed to stop it completely is:
सही उत्तर: घ) 11
Energy lost per plank = ½mv²[1 − (19/20)²] = 0.0975 × ½mv²; planks needed = 1/0.0975 ≈ 10.3, so 11 planks are required.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The work done by a variable force acting along the x-axis is given by the:
सही उत्तर: ग) area under the force–displacement graph
W = ∫F dx, which equals the area under the F–x curve (the area under F–t gives impulse).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A light ball collides elastically head-on with a very heavy body at rest. After the collision the light ball:
सही उत्तर: ग) rebounds with nearly the same speed
For m₁ ≪ m₂ the elastic-collision result v₁ = (m₁ − m₂)u/(m₁ + m₂) ≈ −u: it bounces back with almost its original speed.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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