Science Question Answer (2 Marks)

A pleasant sound is called music. Its like a treat to the ears.
Example:

1. Beats.
2. Tones.

The air particles near the sound producing body vibrate and exchange energy, which is received by our ears and we are able to hear the sounds.

The sensation of frequency is called “pitch” The high frequency indicates high pitch and vice-versa.

1. Woman has short vocal chords. The male vocal chords are between 17mm and 25mm in length whereas of a woman are between 12.5mm and 17.5mm long.
2. Woman produces sound of higher pitch.

1. Loudness is also doubled.
2. Loudness is halved.

Noise pollution has adverse effects physical as well as mental behavior. The constant exposure to noise pollution can create many health related problems like hypertension, insomnia, mental disorder and may even lead to loss of hearing.

Because moon does not have any atmosphere and sound its does not have any medium for sound to travel as sound does not travel in vacuum.

The following measures which can be taken to reduce noise pollution caused by traffic from reaching the residents of the area:

1. The residential area must be declared as no use of horns.
2. The colonies must be established at a distance than the roads.

1. The sound will become loud on increasing the amplitude.
2. The sound will become shrill on increasing the frequency.

The to - and – fro motion of an object in a medium is called vibration.
Amplitude is the largest distance from the mean position of the object.

In case of thunder, we see the lightening first and then the sound of thunder. This is because, the velocity of light in air is 3×108 m/s while the velocity of sound in air is 343 m/s.

1. Sound travels slowest in gas medium.
2. Sound travels fastest in solid medium.

1. The frequency produced by tight and thin vocal chords is quite high. i.e. its high pitch sound.
2. The frequency produced by loose and thick vocal chords is quite low i.e. its low pitch sound.

The Unwanted sound that is unpleasant to ear is called noise.
Example:

1. Loud music
2. The noise of machines.

Because the track is made of metals and sounds travel faster in solids than air. Thus, we can hear the sound of an approaching train even when the train is far off but its sound cannot be heard through the air.

1. Loudness of the sound depends on amplitude.
2. Pitch of the sound depends on frequency.

The Unwanted sound that is unpleasant to ear is called noise. A pleasant sound is called music.
Music can become noise at many instances. Music is of many types and everybody may not like each type of music. When someone listens very loud music, it can be noise for someone else.

This is because the amplitude of vibrations is small when we beat the spoon lightly and so feeble sound is produced but when it is beaten with force then, amplitude of vibrations is large, so loud sound is produced.

The following measures which can be taken to control (or reduce) noise pollution in our surroundings:

1. Ban the use of loudspeakers after 9pm.
2. Ban the use of horns in the areas nearby hospital and school.

Two methods of producing sound are:

1. Beating the plate and spoon against each other.
2. Playing guitar.

Because sound needs material medium to transfer energy from on particle to another particle. If there is vacuum, then no energy transfer takes place.

Ultrasounds mean the sounds having frequency greater than 20,000Hz.
The uses of ultrasound are:

1. They are used in sonography.
2. They used in radars.

The pitch of a sound you hear depends on the frequency of the sound wave. A high frequency sound wave has a high pitch, and a low frequency sound wave has a low pitch.

The length of vocal chords varies in all these three, which is the main reason for different voices. Men have the longest vocal chords, while female have little shorter vocal chords than men and children have the smallest vocal chords.