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 stone is thrown vertically upwards with an initial velocity of 20 m/s. Ignoring air resistance, what is the maximum height reached by the stone? (Take g = 9.8 m/s²)
सही उत्तर: क) 5.0 s
The maximum height is reached when the final velocity of the stone becomes zero. Using the equation v² = u² + 2as, where v=0, u=20 m/s, a=-9.8 m/s², and s is the height, we get s = (v²/2a) = (0² - 20² / (2 * -9.8)) = 20.4 meters. The most tempting answer, 5.0 s, comes from calculating the time to reach maximum height using v=u+at (0 = 20 - 9.8t), which is approximately 2.05 s – not the distance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements BEST describes Ohm's Law?
सही उत्तर: ग) Voltage is directly proportional to current
Ohm’s Law states that Voltage (V) = Current (I) * Resistance (R). Option 2 accurately describes this direct proportionality. The other options incorrectly relate the quantities or describe an inverse relationship.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The potential difference across a resistor of 10 ohms is 5 volts. What is the current flowing through the resistor in amperes?
सही उत्तर: ख) 1.0 A
Using Ohm's Law (V = IR), we have I = V/R, where V is potential difference and R is resistance. Therefore, I = 5 volts / 10 ohms = 0.5 amperes. The other options involve incorrect values for either voltage or resistance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A student measures the period of oscillation of a simple pendulum. The length of the pendulum is 1.0 meter and the acceleration due to gravity (g) is approximately 9.8 m/s². What is the period of oscillation in seconds?
सही उत्तर: क) 1.0 s
The period (T) of a simple pendulum is given by T = 2π√(L/g), where L is the length and g is the acceleration due to gravity. Therefore, T = 2π√1 m / 9.8 m/s² ≈ 1.0 seconds. The other options are incorrect calculations or approximations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform wooden block has dimensions 10 cm x 20 cm x 30 cm. Its density is 700 kg/m³. What is its mass in kilograms?
सही उत्तर: ख) 7 kg
The volume of the block is 10cm * 20cm * 30cm = 6000 cm³ = 0.006 m³. Mass = Density x Volume, so Mass = 700 kg/m³ * 0.006 m³ = 4.2 kg. The other options are incorrect calculations, with one using a unit conversion error and the others providing extremely large mass values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The speed of sound in air at room temperature (approximately 20°C) is approximately 343 m/s. If a stationary observer hears the echo of a thunderclap 10 seconds later, approximately how far away from the observer did the lightning strike? (Assume speed of light is negligible compared to the speed of sound)
सही उत्तर: ख) 10 km
The time taken for the echo to return is 10 seconds. Distance = Speed x Time, so Distance = 343 m/s * 10 s = 3430 meters or 3.43 kilometers. The most tempting answer (5km) is incorrect because it significantly underestimates the distance based on a simple speed-time calculation. 20 km and 50 km are also clearly too high.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A light ray traveling in air is incident on a glass surface at an angle of incidence of 30 degrees. If the refractive index of glass is 1.5, what is the angle of refraction? (Use Snell's law)
सही उत्तर: ख) 30°
Snell’s Law states: n₁sinθ₁ = n₂sinθ₂ where n₁ and n₂ are refractive indices of air and glass respectively, and θ₁ and θ₂ are the angles of incidence and refraction. Here, n₁=1 (approx), n₂=1.5, θ₁=30°. Therefore, 1*sin30° = 1.5 * sinθ₂, so sinθ₂ = 0.333 or θ₂≈24 degrees. The other values are derived from incorrect calculations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A metal block of mass 0.5 kg is heated from 20°C to 100°C. If the specific heat capacity of the metal is 400 J/kg·K, what is the amount of heat energy (in Joules) required to raise its temperature?
सही उत्तर: घ) 800 J
The heat energy (Q) needed to change the temperature of a substance is given by Q = mcΔT, where m is mass, c is specific heat capacity, and ΔT is the change in temperature. In this case, Q = 0.5 kg * 400 J/kg·K * (100°C - 20°C) = 400*80=3200 J. The options listed are incorrect calculations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body of mass 2 kg moves with a velocity of 10 m/s. If the kinetic energy is converted into potential energy at a height of 10 meters (g = 9.8 m/s²), what is the potential energy gained in joules?
सही उत्तर: ग) 200 J
Kinetic Energy = (1/2) * m * v². Here, KE = (1/2) * 2 kg * (10 m/s)² = 100 Joules. Potential energy is given by PE = mgh. With m=2kg, g=9.8m/s² and h=10m, PE = 2*9.8*10 = 196 J. The option 200J and 490J are clearly incorrect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform wooden block rests on a horizontal surface. The coefficient of static friction between the block and the surface is 0.4. What maximum normal force can be applied to the surface to prevent the block from sliding? (Assume g = 9.8 m/s²)
सही उत्तर: क) 1. 2.94 N
The maximum normal force is given by the friction force, which is μs * N, where μs is the coefficient of static friction and N is the normal force. Therefore, N = μs * mg = 0.4 * 20 kg * 9.8 m/s² = 78.4 N. Option 1 (2.94N) is a highly simplified calculation, while options 2,3 and 4 are all significantly different values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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