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 car travels at a constant speed of 30 m/s when suddenly brakes are applied. The deceleration due to braking is 4 m/s². What distance will the car cover before coming to rest?
सही उत्तर: क) 150 m
We can use the equation v² = u² + 2as, where v is final velocity (0 m/s), u is initial velocity (30 m/s), a is deceleration (-4 m/s²), and s is the distance. Rearranging to solve for ‘s’, we get s = (v² - u²) / 2a = (0 - 30²) / (2 * -4) = 900 / 8 = 112.5 meters. The closest answer is 150m, representing a slight misunderstanding in applying the formula.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform wooden block rests on a horizontal surface with a coefficient of static friction (μs) of 0.4. A force ‘F’ is applied horizontally to the block, and it just begins to move. What is the maximum normal reaction force exerted by the surface on the block?
सही उत्तर: क) 8 N
The maximum force of static friction (fs) is given by fs = μs * N, where 'N' is the normal reaction. The block just begins to move when fs equals F. Therefore, F = μs * N. Solving for N gives us N = F/μs = F/0.4. Since we don’t know the value of ‘F’, we can’t calculate a precise numerical answer. However, 16N is the closest to this as it's derived from a force being just about to overcome static friction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A light bulb emits light uniformly in all directions. The intensity of light at a distance of 2 meters from the bulb is 0.1 W/m². What is the total power radiated by the bulb?
सही उत्तर: क) 0.2 W
The power emitted by the bulb is constant and radiates equally in all directions, forming a sphere. The intensity (I) decreases with the square of the distance (r) from the source: I = P/4πr². Therefore, at r=2m, 0.1 W/m² = P/(4π(2)²). Solving for P gives us P = 0.1 * 4π(4) = 1.6π ≈ 5.03W. However, the closest option is 0.4W, indicating a misunderstanding of the problem’s core concept: intensity decreases with distance squared.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A transformer has 200 turns in the primary coil and 800 turns in the secondary coil. If the primary voltage is 220V, what is the approximate voltage in the secondary coil?
सही उत्तर: ख) 880V
The ratio of voltages in a transformer is equal to the ratio of the number of turns. Therefore, V₂/V₁ = N₂/N₁. Solving for V₂, we get V₂ = (N₂/N₁) * V₁. Plugging in the values: V₂ = (800/200) * 220V = 4 * 220V = 880V. The most plausible incorrect option would have a similar ratio or used an inaccurate value of the primary voltage.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform electric field of magnitude 80 N/C is applied parallel to a rectangular plate with sides of length 0.1 m and 0.2 m. What is the force on the side with length 0.1 m?
सही उत्तर: क) 4 N
The force on a charge in an electric field is given by F = qE, where q is the charge and E is the electric field strength. The force on a plate is also equal to its area times the field strength. Since we are using N/C for the field, the force will be in Newtons. For the side with length 0.1 m, the force is F = (charge) * 80 N/C. In this case, since no charge is mentioned, it's implicitly assuming 'q'=1. Therefore Force = 80 N.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Fleming’s left-hand rule relates the force on a current-carrying conductor with its motion and magnetic field. Which of the following correctly describes how this rule determines the direction of the force?
सही उत्तर: क) The thumb points in the direction of velocity, the middle finger in the direction of magnetic field, and the little finger points in the direction of force.
Fleming’s left-hand rule is defined as: Thumb = Velocity, Middle Finger = Magnetic Field, Little Finger = Force. The correct orientation makes sense based on this relationship. The other options misrepresent the directional association between these three vectors.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The velocity of a car moving with uniform acceleration is 4 m/s when the distance traveled in 2 seconds is 25 meters. What is the magnitude of the acceleration?
सही उत्तर: ख) 2 m/s²
We use the kinematic equation: s = ut + (1/2)at², where s=distance, u=initial velocity, a=acceleration, and t=time. Plugging in the given values: 25 = 4t + (1/2)a(2)² => 25 = 4t + 2a. Since the car has uniform acceleration, we can solve for 'a'. Initially velocity is 4 m/s and at t=2s it becomes x. Hence, a = (25-4*2)/2 = (25-8)/2 = 17/2 = 8.5m/s^2. The most tempting incorrect option, 4 m/s², is wrong because the acceleration isn't constant and not equal to the initial velocity.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A vehicle with a mass of 1500 kg accelerates uniformly from rest to a velocity of 36 km/h in 10 seconds. Calculate the net force acting on the vehicle, assuming it is on a level surface. (Take g = 9.8 m/s²)
सही उत्तर: ख) 180 N
The force can be calculated using Newton's second law: F = ma. Here, m = 1500 kg and a = (36 km/h into m/s) / 10 s ≈ 3.6 m/s². Therefore, F = 1500 * 3.6 = 5400 N which is not an option - most likely due to rounding error in the calculation within the question. The correct answer should be approximately 5400 N.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A force of 10 N is applied to a mass on a frictionless surface for 2 seconds. What is the acceleration of the mass? (a) 5 m/s² (b) 10 m/s² (c) 20 m/s² (d) 50 m/s²
सही उत्तर: ख) (b) 10 m/s²
Using Newton’s second law of motion (F = ma), we can calculate acceleration: a = F/m. We are given F=10 N and assuming mass 'm' is 1 kg (though not explicitly stated, it’s implied for this level), then a = 10N / 1kg = 10 m/s².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A light ray traveling from air into glass will (a) continue travelling at the same speed. (b) change its direction and bend towards the normal. (c) change its direction and bend away from the normal. (d) stop completely.
सही उत्तर: ग) (c) change its direction and bend away from the normal.
When a light ray enters glass from air, it slows down and bends towards the normal due to refraction. This is because the speed of light is different in the two mediums. The other options represent incorrect scenarios regarding light behaviour.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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