A tunning fork of frequency 340 Hz resonates in the fundamental mode with an air column of length 125 cm in a cylindrical tube closed at one end. When water is slowly poured in it, the minimum height of water required for observing resonance once again is ___________ cm.

(Velocity of sound in air is 340 ms^$$-$$1)

A liquid of density 750 kgm^$$-$$3 flows smoothly through a horizontal pipe that tapers in cross-sectional area from A₁ = 1.2 $$\times$$ 10^$$-$$2 m² to A₂ = $${{{A_1}} \over 2}$$. The pressure difference between the wide and narrow sections of the pipe is 4500 Pa. The rate of flow of liquid is ___________ $$\times$$ 10^$$-$$3 m³s^$$-$$1.

A uniform disc with mass M = 4 kg and radius R = 10 cm is mounted on a fixed horizontal axle as shown in figure. A block with mass m = 2 kg hangs from a massless cord that is wrapped around the rim of the disc. During the fall of the block, the cord does not slip and there is no friction at the axle. The tension in the cord is ____________ N.

(Take g = 10 ms^$$-$$2)

A car covers AB distance with first one-third at velocity v₁ ms^$$-$$1, second one-third at v₂ ms^$$-$$1 and last one-third at v₃ ms^$$-$$1. If v₃ = 3v₁, v₂ = 2v₁ and v₁ = 11 ms^$$-$$1 then the average velocity of the car is _____________ ms^$$-$$1.