भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – कृषि/वन प्रवेश
Physics · Agriculture, Veterinary & Forestry Entrance · ४२५ प्रश्न
४२५ 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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A train traveling at a constant speed of 60 km/h covers a distance of 30 kilometers in 0.5 hours. What is the acceleration of the train?
सही उत्तर: ख) 6 km/h
Since the train is traveling at a constant speed, its acceleration is zero. The equation distance = speed * time implies that when distance is 30km and time is 0.5 hours, speed should be 60km/h (30/0.5=60). Therefore, 0 km/h is correct.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body of mass 5 kg falls vertically down from a height of 20 meters. Neglecting air resistance, what is the potential energy lost by the body when it reaches the ground?
सही उत्तर: ख) 200 J
The potential energy loss (PE) is calculated using the formula PE = mgh, where m is mass (5 kg), g is acceleration due to gravity (9.8 m/s²), and h is height (20 m). Therefore, PE = 5 * 9.8 * 20 = 980 J. The option '400 J' is incorrect as it doesn’t account for the actual mass and height values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following best describes the concept of ‘inertia’?
सही उत्तर: ख) The force that causes objects to accelerate
Inertia is fundamentally about an object's resistance to being moved or changed. Newton’s First Law of Motion defines inertia perfectly. Options 2 & 3 refer to specific forces and energies, while option 4 describes thermal energy.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform wooden block slides down a plane inclined at an angle of 30 degrees to the horizontal with a constant velocity. The coefficient of kinetic friction between the block and the plane is 0.2. What is the angle of inclination of the plane required for the block to slide down with constant velocity?
सही उत्तर: ख) 30 degrees
The block will slide down with constant velocity when the component of gravity along the plane equals the force of friction. This happens when the angle of inclination is such that sin(θ) = μk, where θ is the angle and μk is the coefficient of kinetic friction. Option A (15 degrees) yields a sine value too small; option C (45 degrees) gives a sine value equal to 1, leading to infinite friction. Option B (30 degrees) also provides a value close to μk, while option D (60 degrees) is significantly larger.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Water is used in hot-water bags because: (a) It expands significantly when heated. b) It has a high specific heat capacity. c) Its freezing point is below room temperature. d) It's a good conductor of heat.
सही उत्तर: ख) (b) It has a high specific heat capacity.
Hot water expands as it gains heat, increasing its volume and thus providing warmth (option 1). Option b describes a property that doesn't directly explain the bag's function. Options c and d are incorrect properties of water.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which list arranges electromagnetic radiations in increasing order of wavelength? (a) Gamma rays, X-rays, Ultraviolet rays, Visible light, b) Visible light, Ultraviolet rays, Infrared rays, Microwaves, c) Microwaves, Infrared rays, Visible light, Ultraviolet rays, d) X-rays, Gamma rays, Infrared rays, Microwaves
सही उत्तर: ख) (b) Visible light, Ultraviolet rays, Infrared rays, Microwaves
The electromagnetic spectrum is arranged from shortest wavelength to longest. Visible light sits in the middle of the range, with gamma rays and X-rays having shorter wavelengths, and microwaves having longer wavelengths (option 1). Options a, c and d misorder the types of radiation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Wien's displacement law, as the temperature of a hot body increases, the wavelength of emitted radiation decreases. Which of the following statements best describes this relationship? (a) Higher temperatures result in longer wavelengths. b) Higher temperatures result in shorter wavelengths. c) Temperature has no effect on the wavelength of emitted radiation. d) Wavelength is inversely proportional to temperature squared.
सही उत्तर: ख) (b) Higher temperatures result in shorter wavelengths.
Wien's displacement law states that the wavelength at which the spectral radiance of black-body radiation is maximum is inversely proportional to the absolute temperature. Therefore, higher temperatures result in shorter wavelengths (option b). Option a is incorrect as it suggests the opposite relationship. Options c and d are incorrect due to not reflecting the law’s core principle.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The time period of a simple pendulum is given by T = 2π√(L/g), where L is the length and g is the acceleration due to gravity. If the length of a simple pendulum is made four times, its time period becomes: (a) 2π√4g (b) 4π√(L/g) (c) 8π√(L/g) (d) 2π√L
सही उत्तर: ग) 8π√(L/g)
The correct formula for the time period of a simple pendulum is T = 2π√(L/g). If the length (L) is multiplied by four, then the time period becomes √4 = 2 times longer. Thus, the new time period is 2π√((4L)/g), which matches option (c).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A car is traveling at a constant speed of 30 m/s when it encounters a hill. The hill increases the car's speed to 40 m/s. What is the average acceleration of the car during this period?
सही उत्तर: ग) 7.14 m/s²
Average acceleration is defined as (final velocity - initial velocity) / time. Here the change in speed is 40m/s-30m/s=10m/s over a period not provided here; however, we can calculate the acceleration using average velocity. Average speed = (30 + 40)/2 = 35m/s. Acceleration = change in velocity / time. Because the problem does not provide time we must solve it differently: Average acceleration = (Final Velocity - Initial Velocity) / Time= (40-30)/Time = 10/Time; therefore the answer is 7.14m/s2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The refractive index of a medium is defined as the ratio of the speed of light in vacuum to the speed of light in that medium. What does this mean?
सही उत्तर: ख) Light travels slower in the medium
The refractive index measures how much slower light travels in a given medium compared to its speed in vacuum. A higher refractive index indicates that light travels slower through the medium. Option 2 is correct.
💬 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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