11.

If we throw a body upwards with velocity of 4 m/s, at what height does its kinetic energy reduce to half of the initial value? ( Take g = 10 ms^-1 )

• 4 m

• 2 m

• 1m

• 0.4 m

We consider a thermodynamic system. If ΔU represents the increase in its internal energy and W the work done by the system, which of the following statements is true?

• ΔU = -W in an adiabatic process

• ΔU = W in an isothermal process

• ΔU = -W in an isothermal process

• ΔU = W in an adiabtic process

Aerofils are so designed that the speed of air

• on top side is more than on lower side

• on top side is less than on lower side

• is same on both sides

• is turbulent

The time of reverberation of a room A is one second. What will be the time (in seconds) of reverberation of a room, having all the dimensions double of those of room A?

• 2

• 4

• $\frac{1}{2}$

• 1

Which of the following circular rods, (given radius r and length l) each made of the same material and whose ends are maintained at the same temperature will conduct most heat?

• r = 2r_o ; l = 2 l_o

• r = 2r_o ; l = l_o

• r = r_o ; l = l_o

• r = r_o ; l = l_o

Which one of the following statements is true?

• Both light and sound waves in air are transverse

• The sound waves in air are longitudinal while the light waves are transverse

• Both light and sound waves in air are longitudinal

• Both light and sound waves can travel in vacuum

Pressure of an ideal gas is increased by keeping temperature constant. What is the effect on kinetic energy of molecules?

• increase

• Decrease

• No change

• Can't be determined

A closed organ pipe of length 20 cm is sounded with tuning fork in resonance. What is the frequency of tuning fork? (v = 332 m/s)

• 300 Hz

• 350 Hz

• 375 Hz

• 415 Hz

When you make ice cubes, the entropy of water

• does not change

• increases

• decreases

• may either increase or decrease depeding on the process used

Given that $\mathrm{y} = \mathrm{A} \sin \left[\left( \frac{2\mathrm{\pi }}{\mathrm{\lambda }} \left(\mathrm{ct} - \mathrm{x}\right) \right)\right]$ , where y and x are measured in metre. Which of the following statements is true?

• The unit of λ is same as that of x and A

• The unit of λ is same as that of x but not of A

• The unit of c is same as that of $\frac{2\mathrm{\pi }}{\mathrm{\lambda }}$

• The unit of ( ct - x ) is same as that of $\frac{2\mathrm{\pi }}{\mathrm{\lambda }}$