A stress that changes the shape of a body without changing its volume is called:
A Tensile stress
B Bulk stress
C Shearing stress
D Longitudinal stress
Shearing stress changes shape → volume remains constant.
The ratio of stress to strain in the elastic region is:
A Breaking stress
B Elastic constant
C Hooke’s law
D Young’s modulus
Young’s modulus = (Longitudinal stress)/(Longitudinal strain).
The point beyond which a material does not obey Hooke’s law is called:
A Elastic limit
B Breaking point
C Plastic limit
D Yield point
Beyond elastic limit, stress–strain proportionality fails.
A metal wire of double length and same material will have:
A Same Young’s modulus
B Double Young’s modulus
C Half Young’s modulus
D Zero Young’s modulus
Young’s modulus is a material constant, independent of dimensions.
The area under a stress–strain curve represents:
A Density
B Elastic limit
C Energy stored per unit volume
D Poisson’s ratio
Work done in stretching = area under curve.
A material that fractures without noticeable deformation is:
A Ductile
B Brittle
C Elastic
D Plastic
Brittle materials break suddenly with minimal elongation.
Rubber has a very high:
A Elastic limit
B Young’s modulus
C Ductility
D Elastic strain limit
Rubber undergoes large elastic deformation before returning to shape.
The dimensional formula of Young’s modulus is same as:
A Force
B Pressure
C Energy
D Velocity
Both have dimension ML⁻¹T⁻².
Breaking stress is defined as:
A Minimum stress before breaking
B Maximum stress a material can bear
C Stress at elastic limit
D Stress at yield point
Breaking stress is the maximum sustainable stress.
Steel is more elastic than rubber because:
A It is stiffer
B It bends more
C It has higher elasticity modulus
D It stretches more
Higher modulus → greater elasticity in physics sense.
Pressure in a fluid at rest depends on:
A Shape of container
B Area of base
C Depth only
D Type of gas above liquid
P = ρgh, depends only on height below free surface.
When area decreases, velocity of a fluid increases. This is due to:
A Bernoulli’s principle
B Continuity equation
C Pascal’s law
D Stokes’ law
A₁v₁ = A₂v₂.
A body appears lighter in fluid because of:
A High density
B Compression
C Buoyant force
D Viscosity
Upward buoyant force reduces apparent weight.
Flow is said to be turbulent when:
A Reynolds number is small
B Velocity is constant
C Reynolds number is large
D Pressure is constant
Re > ~2000 generally indicates turbulence.
The instrument used to measure pressure difference is:
A Barometer
B Manometer
C Thermometer
D Hygrometer
Manometers measure pressure difference between two points.
Lift of an airplane wing is explained through:
A Archimedes’ principle
B Pascal’s law
C Bernoulli’s theorem
D Newton’s third law
Faster airflow on top → lower pressure → lift.
Fluid that shows no change in viscosity with shear rate is:
A Newtonian
B Non-Newtonian
C Ideal fluid
D Perfect fluid
Newtonian fluids follow linear stress–strain relation.
A fluid with zero viscosity is called:
A Real fluid
B Ideal fluid
C Newtonian fluid
D Compressible fluid
Ideal fluids have no viscosity and no internal friction.
Stokes’ law for viscous drag is valid when:
A Reynolds number > 2000
B Reynolds number < 1
C Flow is turbulent
D Fluid is gas only
Requires laminar, extremely low-Re flow.
Capillarity occurs due to:
A Cohesion only
B Adhesion only
C Both adhesion and cohesion
D Hydration
Adhesion causes rise; cohesion shapes meniscus.
Viscosity arises due to:
A Gravity
B Intermolecular forces
C Pressure
D Volume
Internal friction is from molecular interactions.
Stokes’ law holds for:
A Turbulent flow
B High velocity
C Very small spheres at low speeds
D Compressible fluids
Stokes’ law applies to laminar flow at low Reynolds number.
Capillary rise is more in:
A Wide tubes
B Narrow tubes
C Any tube equally
D Rough tubes only
h ∝ 1/r.
Detergents reduce surface tension by:
A Increasing cohesion
B Decreasing adhesion
C Decreasing cohesion
D Increasing temperature
They weaken intermolecular attraction, reducing surface tension.
A drop of water is spherical due to:
A Gravity
B Viscosity
C Surface tension
D Temperature
Surface tension minimizes surface area → sphere.
Temperature increase generally:
A Increases viscosity of liquids
B Decreases viscosity of liquids
C Has no effect
D Makes viscosity infinite
Liquid viscosity decreases with temperature.
Terminal velocity in a viscous medium is zero when:
A Buoyant force > weight
B Weight > drag
C Buoyant force = weight
D Weight = buoyant force + viscous drag
At terminal velocity net force = 0.
Surface energy per unit area equals:
A Viscosity
B Surface tension
C Thermal conductivity
D Stress
Surface energy and surface tension have same value dimensionally.
Soap bubbles form due to:
A Density
B Very high pressure
C Surface tension
D Buoyancy
They minimize energy by forming spherical surfaces.
Viscosity of gases:
A Decreases with temperature
B Increases with temperature
C Zero
D Independent of temperature
Higher temperature → faster molecular motion → more momentum transfer.
Temperature is a measure of:
A Total energy
B Heat
C Average kinetic energy
D Pressure
Temperature relates to average kinetic energy of molecules.
Heat capacity depends on:
A Material only
B Mass only
C Both mass & nature
D Temperature only
Heat capacity C = mc.
Linear expansion is proportional to:
A Volume
B Temperature change
C Density
D Pressure
ΔL ∝ ΔT.
The SI unit of heat is:
A Calorie
B Newton
C Joule
D Watt
Joule is SI unit.
The relation between Cp and Cv for solids is:
A Cp = Cv
B Cp > Cv
C Cp < Cv
D Cp = 0
For solids, difference is negligible.
Specific heat is highest for:
A Iron
B Copper
C Water
D Gold
Water has highest specific heat capacity.
Sublimation involves:
A Solid → liquid
B Liquid → gas
C Solid → gas
D Gas → solid
Direct transition.
Thermal conductivity is lowest in:
A Metals
B Water
C Air
D Glass
Gases are poor conductors.
In conduction, heat flows due to:
A Bulk motion
B Radiation
C Direct contact
D Convection cells
Conduction requires contact.
Latent heat refers to heat used in:
A Temperature change
B Phase change
C Expansion
D Radiation
Latent heat changes state without temperature change.
Pressure of a gas arises due to:
A Weight of gas
B Viscosity
C Molecular collisions with walls
D Surface tension
Molecules exert force during collisions.
RMS speed of gas molecules is proportional to:
A √T
B T
C 1/T
D 1/√T
v_rms = √(3RT/M).
At constant temperature, pressure × volume is constant. This is:
A Charle’s law
B Boyle’s law
C Avogadro’s law
D Gay–Lussac law
Boyle’s law: PV = constant.
Avogadro’s law states:
A PV ∝ T
B Equal volumes contain equal mass
C Equal volumes at STP contain equal number of molecules
D Pressure ∝ temperature
Avogadro: same volume → same number of molecules.
Internal energy of an ideal gas depends on:
A Volume
B Temperature
C Pressure
D Density
U ∝ temperature only.
Zeroth law defines:
A Entropy
B Internal energy
C Temperature
D Heat
It gives basis for temperature measurement.
First law of thermodynamics is based on:
A Conservation of mass
B Conservation of energy
C Conservation of momentum
D Conservation of heat
ΔQ = ΔU + W.
In an isothermal process, ΔU =
A 0
B Maximum
C Minimum
D Infinite
Temperature constant → internal energy constant.
Work done in an adiabatic expansion is:
A Zero
B Maximum
C Minimum
D Negative
No heat exchange → greater work than isothermal.
Efficiency of a Carnot engine depends on:
A Working substance
B Type of fuel
C Temperature difference
D Volume
η = 1 − T₂/T₁.