A certain amount of acoustic energy is emitted in a uniform hemispherical pattern from a point source. At a distance of 5 m form the source the intensity is 5 W/m2. At a distance of 15 m the intensity will be:
None of these
The energy is emitted uniformly over a hemisphere whose surface area is 2πr2.
Since no energy leaks out from the sides of this growing hemisphere we may equate the total energies for any value of r.
A mass m is suspended separately from two springs of constants k1 andk2. Their time periods are found to be T1 and T2 respectively. If the same mass is suspended from the two springs connected in series, then the time period of the combination will be:
Two particles are executing SHM of same amplitude and frequency along the same straight line path. They pass each other when going in opposite directions, each time their displacement is half of their amplitude. What is the phase difference between them?
The figure below shows the wave y = A sin (ωt – kx), at any instant travelling in the +ve x-direction. What is the slope of the curve at B?
What is the ratio of the speed of sound in neon and water vapours at the same temperature? It is nearest to:
In case of the mechanical longitudinal wave y = A sin (ωt – kx) in air (density ρ), what is the relation between displacement amplitude and pressure amplitude?
A man beats a drum at a certain distance from a mountain. He slowly increases the rate of being and finds that the echo is not heard distinctly when the drum beating is at the rate of 40 per minute. He moves by 80 m towards the mountain and finds that the echo is again not heard distinctly when the rate of beating of the drum is 1 per second. What is the original distance of the man from the mountain?
In an experiment, it was found that a tuning fork and a sono-meter emitting its fundamental note, gave 5 beats per second both when the length of the wire was 1 metre and 1.05 metre. The velocity of transverse waves in the sono-meter wire is:
A slab of mass m is released from a height h0 from the top of a spring S’ of force constant K. The maximum compression x of the spring is given by the equation:
A bob of mass m is oscillating as a simple pendulum with maximum amplitude θm. What is the maximum tension in the string?
A 10 W source of sound of frequency 1000 Hz sends out waves in air. The displacement amplitude at a distance of 10 m from source will be: (Given velocity of sound = 350 m/s and density of air = 1.29 kg/m3)