Q.1
Acertain number of spherical drops of a liquidof radius 'r' coalesce to forma single drop ofradius 'R' and volume 'V'. If 'T' is the surfacetension of the liquid, then … [ AIPMT 2014 ]
  • a)
    ch-8_qn-264choice_img_no1.png
  • b) Energy is neither released nor absorbed
    ch-8_qn-264choice_img_no3.png
  • c)
    ch-8_qn-264choice_img_no4.png
  • d)
Q.2
A wind with speed 40 m/s blows parallel to the roof of a house. The area of the roof is 250 mAssuming that the pressure inside the house is atmospheric pressure, the force exerted by thewind on the roof and the direction of the force will be : … [ AIPMT 2015] (ρair = 1.2 kg/m3)
  • a) 2.4 × 105 N, downwards
  • b) 4.8 × 105 N, downwards
  • c) 4.8 × 105 N, upwards
  • d) 2.4 × 105 N, upwards
Q.3
The cylindrical tube of spray pump has radius R, one end of which has n fine holes, each of radius r. If the speed of the liquid in the tube is V, the speed of the ejection of the liquid through the holes is…[ Re. AIPMT 2015]
  • a)
    ch-8_qn-267choice_img_no1.png
  • b)
    ch-8_qn-267choice_img_no2.png
  • c)
    ch-8_qn-267choice_img_no3.png
  • d)
    ch-8_qn-267choice_img_no4.png
Q.4
The Young's modulus of steel is twice that of brass. Two wires of same length and of same area of cross section, one of steel and another of brass are suspended from the same roof. If we want the lower ends of the wires to be at the same level, then the weights added to the steel and brass wires must be in the ratio of : …[Re AIPMT 2015]
  • a) 1 : 1
  • b) 1:2
  • c) 2:1
  • d) 4:1
Q.5
Water rises to height 'h' in capillary tube. If the lengthof capillary tube above the surface of water is madeless than 'h', then – [ Re AIPMT 2015] Solution:
  • a) water does not rise at all.
  • b) water rises upto the tip of capillary tube and thenstarts overflowing like afountain.
  • c) water rises upto the top of capillary tube and stays there without overflowing.
  • d) water rises upto a point a little below the topand stays there.
Q.6
An Two non-mixing liquids of densities ρ and nρ (n > 1) are put in a container. The height ofeach liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floatswith its axis vertical and length pL(p < 1) in thedenser liquid. The density d is equal to :-
  • a) {1 + (n + 1)p}ρ
  • b) {2 + (n + 1)p}ρ
  • c) {2 + (n – 1)p}ρ
  • d) {1 + (n – 1)p}ρ
Q.7
Three liquids of densities ρ1, ρ2 and ρ3(with ρ1 > ρ2 > ρ3), having the same value of surfacetension T, rise to the same height in three identicalcapillaries. The angles of contact θ1, θ2 and θ3 obey… [ NEET II – 2016]
  • a)
    ch-8_qn-273choice_img_no1.png
  • b)
    ch-8_qn-273choice_img_no2.png
  • c)
    ch-8_qn-273choice_img_no3.png
  • d)
    ch-8_qn-273choice_img_no4.png
Q.8
A U tube with both ends open to the atmosphere, ispartially filled with water. Oil, which is immiscible withwater, is poured into one side until it stands at adistance of 10 mm above the water level on the otherside. Meanwhile the water rises by 65 mm from itsoriginal level (see diagram). The density of the oil is ..[ NEET 2017]
ch-8_que_no-274_img_no1.png
  • a) 650 kg m-3
  • b) 425 kg m-3
  • c) 800 kg m-3
  • d) 928 kg m-3
Q.9
The bulk modulus of a spherical object is ‘B’. If it issubjected to uniform pressure ‘p’, the fractionaldecrease in radius is…[NEET 2017]
  • a)
    ch-8_qn-275choice_img_no1.png
  • b)
    ch-8_qn-275choice_img_no2.png
  • c)
    ch-8_qn-275choice_img_no3.png
  • d)
    ch-8_qn-275choice_img_no4.png
Q.10
A uniform cylinder of length L and mass M having cross - sectional area A is suspended, with its length vertical, from a fixed point by a massless spring, such that it is half submerged in a liquid of density σ at equilibrium position. The extension x0 of the spring when it is in equilibrium is … [ IIT Mains -2013]Here k is spring constant
  • a)
    ch-8_qn-276choice_img_no1.png
  • b)
    ch-8_qn-276choice_img_no2.png
  • c)
    ch-8_qn-276choice_img_no3.png
  • d)
    ch-8_qn-276choice_img_no4.png
Q.11
Assume that a drop of liquid evaporates by decrease in its surface energy. So that its temperatureremains unchanged. What should be the minimum radius of the drop for this to be possible? Thesurface tension is T, density of liquid is ρ and L is its latent heat of vaporization.…[ IIT Mains 2013]
  • a)
    ch-8_qn-277choice_img_no1.png
  • b)
    ch-8_qn-277choice_img_no2.png
  • c)
    ch-8_qn-277choice_img_no3.png
  • d)
    ch-8_qn-277choice_img_no4.png
Q.12
One end of a horizontal thick copper wire of length 2L and radius 2R is welded to an end of another horizontal thin copper wire of length L and radius R. When the arrangement is stretched by applying forces at two ends, the ratio of the elongation in the thin wire to that in the thick wire is
  • a) 0.25
  • b) 0.50
  • c) 2.00
  • d) 4.00
Q.13
than one correct answer Q279) A solid sphere of radius R and density ρ is attached to one end of a mass-less spring of force constant k. The other end of the spring is connected to another solid sphere of radius R and density 3ρ. The complete arrangement is placed in a liquid of density 2ρ and isallowed to reach equilibrium. The correct statement(s) is (are)
  • a) the net elongation of the spring is
    ch-8_qn-279choice_img_no1.png
  • b) the net elongation of the spring is
    ch-8_qn-279choice_img_no2.png
  • c) the light sphere is partially submerged.
  • d) the light sphere is completely submerged
Q.14
A glass capillary tube is of the shape of a truncated cone with an apex angle α so that itstwo ends have cross sections of different radii. When dipped in water vertically, waterrises in it to a height h, where the radius of its cross section is b. If the surface tension of water is S, its density is ρ , and its contact angle with glass is θ, the value of h will be (g is the acceleration due to gravity)[ IIT Advance 2014]
ch-8_que_no-280_img_no1.png
  • a)
    ch-8_qn-280choice_img_no1.png
  • b)
    ch-8_qn-280choice_img_no2.png
  • c)
    ch-8_qn-280choice_img_no3.png
  • d)
    ch-8_qn-280choice_img_no4.png
Q.15
RAPH A spray gun is shown in the figure where a piston pushes air out of a nozzle. A thin tube ofuniform cross section is connected to the nozzle. The other end of the tube is in a small liquidcontainer. As the piston pushes air through the nozzle, the liquid from the container rises intothe nozzle and is sprayed out. For the spray gun shown, the radii of the piston and the nozzleare 20 mm and 1 mm respectively. The upper end of the container is open to the atmosphere.[ IIT Advance 2014] Q281) If the piston is pushed at a speed of 5 mms−1, the air comes out of the nozzle with a speed of
ch-8_que_no-281_img_no1.png
  • a) 0.1 ms−1
  • b) 1 ms−1
  • c) 2 ms−1
  • d) 8 ms−1
Q.16
than one correct option Q282) In plotting stress versus strain curves for two materials P and Q, a student by mistake puts strain on the y-axis and stress on the x-axis as shown in the figure. Then the correct statement(s) is (are) …[ IIT Advance 2015]
ch-8_que_no-282_img_no1.png
  • a) P has more tensile strength than Q
  • b) P is more ductile than Q
  • c) P is more brittle than Q
  • d) The Young’s modulus of P is more than that of Q
Q.17
A spherical body of radius R consists of a fluid of constant density and is in equilibrium under its own gravity. If P(r) is the pressure at r(r < R), then the correct option(s) is(are) …[ IIT Advance 2015]
  • a) P(r = 0) = 0
    ch-8_qn-283choice_img_no2.png
  • b)
    ch-8_qn-283choice_img_no3.png
  • c)
    ch-8_qn-283choice_img_no4.png
  • d)
Q.18
than one correct answer Q284) Two spheres P and Q of equal radii have densities ρ1 and ρ2 , respectively. The spheres are connected by a massless string and placed in liquids L1 and L2 of densities σ1 and σ2 and viscosities η1 and η2, respectively. They float in equilibrium with the sphere P in L1 and sphere Q in L2 and the string being taut (see figure). If sphere P alone in L2 has terminal velocity P V and Q alone in L1 has terminal velocity V Q, then
ch-8_que_no-284_img_no1.png
  • a)
    ch-8_qn-284choice_img_no1.png
  • b)
    ch-8_qn-284choice_img_no2.png
  • c)
    ch-8_qn-284choice_img_no3.png
  • d)
    ch-8_qn-284choice_img_no4.png
Q.19
Consider an expanding sphere of instantaneous radius R whose total mass remains constant. The expansion is such that the instantaneous density ρ remains uniform throughout the volume. The rate of fractional change in density is constant. The velocity v of any point on the surface of the expanding sphere is proportional to … [ IIT Advance 2017]
ch-8_que_no-287_img_no1.png
  • a) R3
  • b) 1/R
  • c) R
  • d) R2/3
Q.20
The terminal speed of rain drop of radius 0.3mm in air is 1 m/sec. If the coefficient of viscosity of air is 18×10⁻⁵ poise, then the viscous force on the drop is [ PET 1990]
  • a) 101.73 ×10⁻⁴ dyne
  • b) 101.73 ×10⁻⁵ dyne
  • c)16.95 ×10⁻⁵ dyne
  • d)16.95 ×10⁻⁴ dyne
Q.21
A straight bimetallic strip is made of copper ( coefficient of linear expansion 1.62×10⁻⁶ K-1) and iron ( coefficient of linear expansion 1.2×10⁻⁶ K-1) If this strip is heated to a high temperature, it will [ SCRA 1994]
  • a) bend with iron on the outer side
  • b) bend with copper on the outer side
  • c) remain in a straight condition
  • d) be twisted to a helix
Q.22
An iron tyre is to be fitted on a wooden wheel 1.0 m in diameter, the diameter of the tyre is 6 mm smaller than that of the wheel. The tyre should be heated so that its temperature increases by a minimum of :.. ( coefficient of expansion of iron is 3.6×10⁻⁵ per °C) [ CPMT 1989]
  • a) 167°C
  • b) 334°C
  • c) 500 °C
  • d) 1000 °C
Q.23
The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 × 10⁻¹¹ Pa-1 anddensity of water is 103 kg/mWhat fractional compression of water will be obtained at the bottom ofthe ocean?
  • a) 1.4 × 10⁻²
  • b) 0.8 × 10⁻²
  • c) 1.0 × 10⁻²
  • d) 1.2 × 10⁻²
Q.24
The value of coefficient of volume expansion ofglycerin is 5 × 10⁻⁴ K-The fractional change inthe density of glycerin for a rise of 40°C in itstemperature, is :-
  • a) 0.010
  • b) 0.015
  • c) 0.020
  • d) 0.025
Q.25
The compressibility of water is 4 × 10⁻⁵ per unit atmospheric pressure. The decrease in volume of 100 cm3 of water under a pressure of 100 atmosphere will be [ CBSE_PMT 1990]
  • (a) 0.4cm3
  • (b) 4x 10⁻⁵cm3
  • (c) 0.025cm3
  • (d) 0.004cm3
Q.26
An iron rod of length 2m and cross -sectional area of 50 mm2is stretched by 0.5mm, when a mass of 250kg is hung from its lower end. Young's modulus of iron rod is [ AFMC 1999]
  • a) 19.6×10²⁰N/m²
  • b) 19.6×10¹⁸N/m²
  • c)19.6×10¹⁰N/m²
  • d)19.6×10¹⁵N/m²
Q.27
A black body has maximum wavelength λm at temperature 2000 K. Its corresponding wavelength at temperature 3000 K will be [2001]
  • a) (3/2) λm
  • b) (2/3) λm
  • c)(4/9) λm
  • d)(9/4) λm
Q.28
Wien's law is concerned with [ CBSE-PMT 2002]
  • a) relation between emissivity and absorptivity of a radiating surface
  • b) total radiation, emitted by a hot surface
  • c) an expression for spectral distribution of energy of a radiation from any source
  • d) a relation between the temperature of a black body and the wavelength at which there is maximum radiant energy per unit wavelength
Q.29
The upper end of wire 1 meter long and 2 mm radius is clamped. the lower end is twisted through an angle of 45°. The angle of shear is [ MPPMT 1990]
  • a)0.09°
  • b) 0.9°
  • c)9°
  • d)90°
Q.30
A metal ball of surface area 200 square cm, temperature 527 °C is surrounded by a vessel at 27°C. If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is σ=5.67×10⁻⁸ S.I. unit
  • a) 108 joule approximately
  • b) 168 joule approximately
  • c)182 joule approximately
  • d)192 joule approximately
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