SPSC PHYSICS 25 YEARS PAST PAPERS
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
جوہری ری ایکٹر میں ماڈریٹر کا مقصد ______ ہے؟
Slow down fast neutrons to increase the probability of capture by uranium
Shield the reactor operator from dangerous radiation
Provide neutrons for the fission process
None of these
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Explanation
Moderators (like water or graphite) reduce the speed of fast-moving neutrons. It making them more likely to be absorbed by uranium nuclei. This increases the efficiency of the fission reaction, sustaining a controlled chain reaction in the reactor.
اگر تاریک معاملہ موجود نہیں تھا تو یہ امکان ہے کہ ______؟
The universe would expand forever
The night sky would be brighter
The universe would begin contracting soon
None of these
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Explanation
Dark matter provides additional gravitational pull, helping galaxies stay bound and influencing cosmic expansion. Without dark matter , gravitational attraction might be weaker, and the universe could slow down its expansion and potentially start contracting.
4 J
20000 J
40000 J
None of these
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Explanation
To find the stored energy, we can use the formula:
Energy (E) = 0.5 × Capacitance (C) × Voltage² (V²)
Given:
C = 20 F
V = 200 V
E = 0.5 × 20 F × (200 V)²
= 0.5 × 20 × 40,000
= 400,000 J
Must be transverse
Has motionless points that are closer than half a wavelength
Can be constructed from two similar waves travelling in opposite directions
None of these
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Explanation
A standing wave is formed by the interference of two waves with the same frequency and amplitude moving in opposite directions. This results in nodes (motionless points) and antinodes (points of maximum displacement) at fixed positions.
افقی محوروں پر دو یکساں دائرے محو ہیں جو ان کی سطحوں پر ٹینجینٹ ہیں۔ ایک طویل مدت کے ساتھ ایک ہے جس میں _______ ہے؟
The larger radius
The larger rotational inertia
The smaller mass
None of these
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Explanation
The period of a physical pendulum depends on the rotational inertia and the distance from the pivot. A larger radius increases the moment of inertia, leading to a longer period of oscillation.
ایک انقلاب ______ جیسا ہے؟
π/2 rad
2π rad
1 rad
None of these
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Explanation
One complete revolution (360°) in radians is given by 2 π 2pi radians. This is because the circumference of a unit circle is 2 π 2pi , which corresponds to one full rotation.
کسی دیئے گئے فوری طور پر کسی شے کی رفتار اس کے ______ سے آزاد ہے؟
Acceleration
Velocity
Mass
None of these
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Explanation
Momentum (p = m v p = mv but not directly on its acceleration. Acceleration affects how momentum changes over time, but at a given instant, momentum is independent of acceleration.
چلتی شے کو روکنے کے لئے درکار کام کی مقدار ______ کے برابر ہے؟
The mass of the object times its acceleration
The velocity of the object
The kinetic energy of the object
None of these
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Explanation
Work required to stop an object is equal to the change in its kinetic energy (Work-Energy Theorem). Since kinetic energy is given by K E = 1 2 m v 2 KE = frac{1}{2} m v^2 work needed to bring the object to rest is equal to its initial kinetic energy.
مختصر اسٹاپ پر ایک لائن ڈرائیو اسی اونچائی پر پکڑی گئی تھی جیسا کہ یہ اصل میں مارا گیا تھا۔ اس کی پوری پرواز کے دوران کشش ثقل کے ذریعہ کیا گیا ہے اور ہوا کے خلاف مزاحمت کے ذریعہ بالترتیب کام کیا گیا ہے _____؟
Positive; negative
Zero; positive
Zero; negative
None of these
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Explanation
The work done by gravity is zero because gravity is a conservative force, and the ball returns to the same height where it started. The work done by air resistance is negative because it always opposes the motion, reducing the ball’s kinetic energy.
ایک شے مستقل رفتار سے دائرے میں حرکت پذیر ہے ______؟
Has an acceleration of constant magnitude
Is held to its path by centrifugal force
Must have only one force acting on it
None of these
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Explanation
An object in uniform circular motion experiences centripetal acceleration, which always points toward the center of the circle. The magnitude of this acceleration remains constant , but its direction continuously changes.
