Consider a 72 cm long wire AB as shown in the figure. The galvanometer jockey is placed at P on AB at a distance x cm from A. The galvanometer shows zero deflection.


The value of x, to the nearest integer, is ___________.

A galaxy is moving away from the earth at a speed of 286 kms^$$-$$1. The shift in the wavelength of a redline at 630 nm is x $$\times$$ 10^$$-$$10 m. The value of x, to the nearest integer, is ____________. [Take the value of speed of light c, as 3 $$\times$$ 10⁸ ms^$$-$$1]

A TV transmission tower antenna is at a height of 20 m. Suppose that the receiving antenna is at.

(i) ground level

(ii) a height of 5 m.

The increase in antenna range in case (ii) relative to case (i) is n%.

The value of n, to the nearest integer, is ___________.

A ball of mass 4 kg, moving with a velocity of 10 ms^$$-$$1, collides with a spring of length 8 m and force constant 100 Nm^$$-$$1. The length of the compressed spring is x m. The value of x, to the nearest integer, is ____________.