1.What is the SI unit of Young’s modulus of elasticity?

2.A steel wire of length 2.0 m and cross-sectional area 1.0e-6 m^2 is stretched by 1.0 mm by an applied tensile force. If Young’s modulus of steel is 2.0e11 Pa, calculate the applied tensile force F in Newtons (N).

3.Why are two identical wires (reference wire and experimental wire) suspended side-by-side from the same rigid support in Searle’s apparatus?

4.A metallic rod of Young’s modulus Y = 1.2e11 Pa is subjected to a tensile strain of 5.0e-4. Calculate the strain energy stored per unit volume (energy density) in J m^-3.

5.On a tensile stress-strain graph of a ductile metal, what does the area under the linear elastic portion represent?

6.Two wires A and B are made of the same metal. Wire A has twice the length and half the diameter of wire B. If identical loads are applied, what is the ratio of extension ΔL_A / ΔL_B?

7.In a Searle’s apparatus experiment, a load of mass 4.0 kg produces an extension of 0.80 mm in a wire of length 3.0 m and diameter 0.50 mm. Calculate the experimental Young’s modulus Y in units of 10^11 Pa. (Take g = 9.8 m s^-2, pi = 3.1416).

8.What is the SI unit of the coefficient of dynamic viscosity (η)?

9.Calculate the viscous drag force F_d in Newtons acting on a spherical metal ball of radius 2.0 mm falling at 0.050 m s^-1 through a heavy oil of viscosity η = 0.80 Pa s. (Take pi = 3.1416).

10.How does the terminal velocity v_t of a sphere falling through a viscous fluid depend on its radius r?

11.A steel sphere (density ρ = 7800 kg m^-3) of radius 1.5 mm falls with terminal velocity 0.040 m s^-1 in a liquid of density σ = 1200 kg m^-3. Calculate the coefficient of viscosity η of the liquid in Pa s. (Take g = 9.8 m s^-2).

12.In Poiseuille’s formula for laminar volume flow rate Q = (π P r^4) / (8 η L), how does Q change if the radius r of the tube is doubled while pressure difference P and length L remain constant?

13.What happens to the viscosity of liquids and gases as temperature increases?

14.Why must the falling sphere in Stokes’ method be dropped along the central axis of a wide glass cylinder rather than near the container walls?

15.What are the dimensions of surface tension (γ)?

16.Calculate the excess pressure ΔP in Pascals (Pa) inside a spherical soap bubble of radius 2.0 cm formed in air, given the surface tension of soap solution is γ = 0.030 N m^-1.

17.A clean glass capillary tube of radius r = 0.30 mm is dipped vertically into pure water (surface tension γ = 0.0735 N m^-1, density ρ = 1000 kg m^-3, contact angle θ = 0°). Calculate the capillary rise h in centimeters (cm). (Take g = 9.8 m s^-2).

18.What causes the meniscus of mercury in a glass capillary tube to be convex with a contact angle θ > 90° and exhibit capillary depression?

19.A thin microscope glass slide of length 8.0 cm is held vertically such that its bottom edge just touches water. If the slide thickness is negligible, what downward force in milliNewtons (mN) is exerted on the slide by surface tension? (Take γ = 0.0725 N m^-1).

20.Calculate the work done W in microJoules (µJ) required to blow a soap bubble of radius 5.0 cm from a flat soap film, given surface tension of soap solution γ = 0.030 N m^-1. (Take pi = 3.1416).