Properties of Solids and Liquids

37 solved questions 2 tests

Ask a question

Take chapter test ← Previous Next chapter →

A small sphere of radius 'r' falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to Answer: 2. r⁵ At terminal velocity, heat is produced at the rate equal to the power of the viscous force: P=F v_t=6πη r v_t² . Terminal velo... Viscosity, Stokes' law, terminal velocity, streamline and turbulent flow, critical velocity 1 answer
A U tube with both ends open to the atmosphere, is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10 mm above the water level on the other side. Meanwhile the water rises by… Answer: 3. 928 kg m ⁻³ Key idea: pressure at the same level in the same liquid is equal. Take points B (oil-water interface, left) and C (sa... Fluid pressure, Pascal's law and applications 1 answer
The bulk modulus of a spherical object is 'B'. If it is subjected to uniform pressure 'p', the fractional decrease in radius is : Answer: 3. p/3B Key idea: B=p/Δ V/V , and for a sphere V∝ r³ , so Δ V/V=3Δ r/r . Δ r/r=1/3Δ V/V=p/3B . Elastic behaviour, stress-strain, Hooke's law, Young's, bulk and rigidity moduli 1 answer
A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be : Answer: 3. 1800 Key idea: power radiated P=σ AT⁴∝ r²T⁴ . Radius halved gives factor 1/4 ; temperature doubled gives factor 2⁴=16 . P'=450×1/... Heat transfer: conduction, convection, radiation 1 answer
Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are K_1 and K_2. The thermal conductivity of the composite rod will be : Answer: 4. K₁+K₂/2 Key idea: the two rods are side by side, so heat flows through them in parallel, and the conductances add. Let each rod h... Heat transfer: conduction, convection, radiation 1 answer
A body cools from a temperature 3T to 2T in 10 minutes. The room temperature is T. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next 10 minutes will be Answer: 1. 3/2T Use Newton's law in the average form: rate of fall =k (mean temperature-T) . First 10 min: 3T-2T/10=k(3T+2T/2-T)=k·3/2T , so... Heat transfer: conduction, convection, radiation 1 answer
Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at 100 °C, while the other one is at 0 °C. If the two bodies are brought into contact, then, assuming no heat loss, the final common t… Answer: 1. more than 50 °C A body with larger heat capacity changes temperature less for the same heat exchanged. The 100 °C body has the la... Specific heat capacity, calorimetry, change of state, latent heat 1 answer
A rectangular film of liquid is extended from (4 cm × 2 cm) to (5 cm × 4 cm). If the work done is 3×10^-4 J, the value of the surface tension of the liquid is Answer: 1. 0.125 N m ⁻¹ Work done in stretching a liquid film is W=T Δ A , where the film has two free surfaces, so Δ A=2×(change in area) .... Surface energy, surface tension, angle of contact, excess pressure, drops, bubbles, capillary rise 1 answer
Three liquids of densities ρ_1,ρ_2 and ρ_3 (with ρ_1>ρ_2>ρ_3), having the same value of surface tension T, rise to the same height in three identical capillaries. The angles of contact θ_1,θ_2 and θ_3 obey Answer: 1. 0≤θ₁<θ₂<θ₃<π/2 Capillary rise is h=2Tcosθ/rρ g . Here h , T and r are the same for all three liquids, so cosθ∝ρ . Since the liqui... Surface energy, surface tension, angle of contact, excess pressure, drops, bubbles, capillary rise 1 answer
Two non-mixing liquids of densities ρ and nρ (n > 1) are put in a container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL (p < 1) in the… Answer: 4. \1+(n-1)p\ρ Key idea: weight of cylinder equals total buoyant force. Length pL is in the denser liquid ( nρ ); remaining (1-p)L i... Fluid pressure, Pascal's law and applications 1 answer
A piece of ice falls from a height h so that it melts completely. Only one - quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is : [Latent heat of ice is 3.4×10^5 J/kg… Answer: 3. 136 km Key idea: loss in potential energy mgh becomes heat; one-quarter of it melts the ice. 1/4mgh=mL⇒ h=4L/g=dfrac4×3.4×10⁵10=1... Specific heat capacity, calorimetry, change of state, latent heat 1 answer
Coefficient of linear expansion of brass and steel rods are α_1 and α_2. Lengths of brass and steel rods are l_1 and l_2 respectively. If (l_2 - l_1) is maintained same at all temperatures, which one of the following relations holds good ? Answer: 4. α₁ l₁ = α₂ l₂ Key idea: the difference of lengths stays constant only if both rods expand by the same amount. Δ l₁=Δ l₂⇒ l₁α₁Δ T=... Heat, temperature and thermal expansion 1 answer
A black body is at a temperature of 5760 K. The energy of radiation emitted by the body at wavelength 250 nm is U_1, at wavelength 500 nm is U_2 and that at 1000 nm is U_3. Wien's constant, b = 2.88×10^6 nmK. Which of the following is correct ? Answer: 4. U₂ > U₁ Key idea: Wien's law λ_m T=b gives the wavelength of peak emission. λ_m=dfrac2.88×10⁶5760=500 nm. Emission is maximum at... Heat transfer: conduction, convection, radiation 1 answer

← Previous

Page 2 of 2