91) A meteor of mass ‘m’ having a speed ‘v’ at infinity reaches the surface of the earth with a speed of (ve is escape speed from the earth’s surface)
A) 
B) 
C) 
D) 
View Answer
D)
Explanation:Energy conservation:
✔️ Answer: D
92) The work to be done to produce a strain of 
in a steel wire of mass 2.96 kg and density 7.4 is (Young’s modulus of steel = )
in a steel wire of mass 2.96 kg and density 7.4 
is (Young’s modulus of steel = 
)View Answer
A) 0.04 kJ
Explanation:Energy:
Compute:
0.04 kJ
✔️ Answer: A
93) A wooden block of outer volume 1 litre and specific gravity having a cavity floats with half of its volume immersed in water. Then the volume of the cavity is
having a cavity floats with half of its volume immersed in water. Then the volume of the cavity is94) When ‘n’ identical mercury drops combine to form a single big drop
95) The temperature of a body shown by a faulty Celsius thermometer is 49 °C and by a correct Fahrenheit thermometer is 122 °F. The correction to be applied to the faulty thermometer is
96) If the radiation emitted by a perfect radiator has maximum intensity at a wavelength of 2900 Å, the intensity of radiation emitted by it is (Stefan-Boltzmann’s constant = 5.67 × 10⁻⁸ Wm⁻²K⁻⁴ and Wein’s constant = 2.9 × 10⁻³ mK)
A) 
Wm⁻²
B) 5.67 Wm⁻²
C) 5670 Wm⁻²
D) 2.9 Wm⁻²
View Answer
A)
Wm⁻²Explanation:λ_max = 2900 Å = 2.9×10⁻⁷ m
Using Wien’s law:
λT = 2.9×10⁻³
⇒ T = (2.9×10⁻³) / (2.9×10⁻⁷) = 10⁴ K
Using Stefan-Boltzmann law:
E = σT⁴
= 5.67×10⁻⁸ × (10⁴)⁴
= 5.67×10⁻⁸ × 10¹⁶
= 5.67×10⁸ W/m²
97) The ratio of the work done, change in internal energy and heat absorbed when a diatomic gas expands at constant pressure is
98) If the temperature of a gas is increased from 127 °C to 527 °C, then the rms speed of the gas molecules
A) increases by 4 times
B) becomes 
times
C) becomes half
D) decreases by times
View Answer
B) becomes
timesExplanation:Temperature ratio:
400K → 800K
Speed ∝ √T ⇒ √2
✔️ Answer: B
99) An air column in a tube of length 50 cm, closed at one end is vibrating in its fifth harmoniC.The phase difference between a particle at the open end and a particle at 42 cm from the open end is
100) A metal rod of length 125 cm is clamped at its midpoint. If the speed of the sound in the metal is 5000ms⁻¹, then the fundamental frequency of the longitudinal vibrations of the rod is
View Answer
A) 2 kHz
Explanation:Frequency:
Compute:
2 kHz
✔️ Answer: A
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