Timbre (quality) of sound depends on the waveform (shape) and harmonic content, so 'shape of the wave' is correct.
1004
The power of a sound from the speaker of a radio is 20 milliwatt. By turning the knob of the volume control the power of the sound is increased to 400 milliwatt. The power increase in decibels as compared to the original power is
Sound requires a material medium to propagate; it cannot travel through vacuum, so option D is correct.
1008
27. An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km, it blows a whistle whose echo is heard by the driver after 5 seconds. If the speed of sound in air is 330 m/s, the speed of engine is
Using the echo travel time and the relative motion of the source towards the hill, solving the distances gives the engine speed as 40 m/s.
1009
Two men stand a certain distance apart beside a long metal fence on a still day. One man places his ear against the fence while the other gives the fence a sharp knock with a hammer. Two sounds separated by a time interval of 0.5 second are heard by the first man. If the velocity of sound in air is 330 ms^-1 and in the metal 5280 ms^-1, how far apart are the men?
