Pakistan MCQs

Viscosity represents internal friction between layers.
More viscous fluids resist deformation more strongly.

Streamline or laminar flow has ordered layers.
Turbulent flow contains irregular fluctuations and mixing.

Cohesive molecular forces create surface tension.
It makes a liquid surface behave like a stretched membrane.

Elastic deformation is reversible within the elastic limit.
Beyond that limit, permanent deformation may occur.

Rotational dynamics gives τ=Iα.
τ=3×4 = 12 N·m.

Opposing torques subtract.
The net magnitude is 15-9 = 6 N·m.

Net work equals the change in kinetic energy.
Kf=20+80 = 100 J.

ΔK=½m(v²-u²).
With m=2, ΔK=49-9 = 40 J.

Momentum is p=mv.
P=6×4 = 24 kg·m/s.

Impulse equals change in momentum.
J=3(8-2)=18 N·s.

Impulse is FΔt for constant force.
50×0.2 = 10 N·s.

Conserve momentum: 2×6 = (2+4)v.
V=12/6 = 2 m/s.