भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – IT प्रवेश
Physics · IT Entrance – B.Sc. CSIT, BIT & BCA · ३९१ प्रश्न
३९१ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान: 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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The acceleration due to gravity at a height equal to the radius of the Earth (h = R) above the surface is:
सही उत्तर: घ) g/4
g' = g R²/(R + h)² = g R²/(2R)² = g/4. The value g/9 would apply at a height of 2R.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Torque has the same dimensions as:
सही उत्तर: ग) Work
Torque = force × perpendicular distance, giving [ML²T⁻²], the same as work or energy. However, torque is a vector and is written in N·m, not in joules.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When a spinning ice skater pulls her arms inward, her angular velocity:
सही उत्तर: ख) Increases
With no external torque, angular momentum L = Iω is conserved. Pulling arms in decreases the moment of inertia I, so ω increases.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The moment of inertia of a uniform solid sphere of mass M and radius R about its diameter is:
सही उत्तर: क) (2/5)MR²
For a solid sphere I = (2/5)MR² about a diameter. (2/3)MR² is the value for a thin hollow spherical shell.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The moment of inertia of a thin circular ring of mass M and radius R about an axis through its centre perpendicular to its plane is:
सही उत्तर: घ) MR²
All the mass of a ring lies at distance R from the axis, so I = MR². ½MR² is the result for a uniform disc about the same axis.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a perfectly elastic collision, which quantities are conserved?
सही उत्तर: ग) Both linear momentum and kinetic energy
In an elastic collision both total momentum and total kinetic energy are conserved. In an inelastic collision only momentum is conserved and some kinetic energy is converted to other forms.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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If the momentum of a body is doubled (mass unchanged), its kinetic energy becomes:
सही उत्तर: ख) 4 times
KE = p²/2m, so doubling p makes KE four times larger. The tempting answer 2 times would apply only if KE were directly proportional to p.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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One horsepower (hp) is approximately equal to:
सही उत्तर: क) 746 W
1 hp ≈ 746 W. The watt is the SI unit of power, equal to 1 joule per second.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A person of mass 60 kg stands in a lift accelerating upward at 2 m/s². Taking g = 10 m/s², the apparent weight of the person is:
सही उत्तर: ग) 720 N
For upward acceleration, N = m(g + a) = 60 × 12 = 720 N. 480 N, i.e. m(g − a), would be the reading if the lift accelerated downward.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A net force of 10 N acts on a body of mass 2 kg. Its acceleration is:
सही उत्तर: ख) 5 m/s²
From F = ma, a = F/m = 10/2 = 5 m/s². Multiplying instead of dividing gives the wrong answer 20 m/s².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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