11.

A steel wire of 1 m long and l mm² cross-section area is hanged from rigid end when weight of 1 kg is hang from it, then change in length will be

(Young's coefficient for wire Y = 2 x 10¹¹ N/m² )

• 0.5 mm

• 0.25 mm

• 0.05 mm

• 5 mm

When an open organ is dipped in water upto half of its height, then its frequency will become

• half

• double

• remain same

• four time

A sound source producing waves of frequency 300 Hz and wavelength lm observer is stationary, while source is going away with the velocity 30 m is, then apparent frequency heared by the observer is

• 270 Hz

• 273 Hz

• 383 Hz

• 300Hz

A mass of 1 kg is suspended from a spring of force constant 400 N, executing SHM total energy of the body is 2J, then maximum acceleration of the spring will be

• 4 m/s²

• 40 m/s²

• 200 m/s²

• 400 m/s²

Vibrations of rope tied by two rigid ends shown by equation y = cos 2πt sin2πx, then minimum length of the rope will be

• 1 m

• $\frac{1}{2}\mathrm{m}$

• 5 m

• 2πm

50 g ice at 0°C in insulator vessel, 50 g water of 100^oC is mixed in it, then final temperature of the mixture is (neglect the heat loss)

• 10^oC

• 0^o << T_m < 20^oC

• 20^oC

• above 20^oC

Linear density of a string of is 1.3 x 10^-4 kg/m and wave equation is y = 0.021 sin (x + 30t ), Find, the tension in the string where, x in metre and t in second

• 0.12 N

• 0.21 N

• 1.2 N

• 0.012 N

An observer is approaching with velocity v towards a light source. If the velocity of light is c, then velocity of light with respect to observer will be

• c - v

• c

• c + v

• $\sqrt{1 - \raisebox{1ex}{${\mathrm{v}}^2$}\!\left/ \!\raisebox{-1ex}{${\mathrm{c}}^2$}\right.}$

The angular amplitude of a simple pendulum is θ₀. The maximum tension in its string will be

• mg (1 - θ₀)

• mg (1 + θ₀ )

• $\mathrm{mg} \left(1- {\mathrm{\theta }}_0^2\right)$

• $\mathrm{mg} \left(1 + {\mathrm{\theta }}_0^2\right)$

During an adiabatic process, the pressure of a gas is found to be proportional to the cube of absolute temperature. The ratio $\frac{{\mathrm{C}}_{\mathrm{P}}}{{\mathrm{C}}_{\mathrm{V}}}$ for the gas is

• $\frac{4}{3}$

• 2

• $\frac{5}{3}$

• $\frac{3}{2}$