English Medium कक्षा ९ - CBSE Question Bank Solutions for Science

How is sound produced? Explain with the help of an example.

How does sound from a sound producing body travel through air to reach our ears? Illustrate your answer with the help of a labelled diagram.

Fill in the blank with suitable word.
When the frequency of the sound is increased, the wavelength ____________.

Draw the sketches of two waves A and B such that wave A has twice the wavelength and half the amplitude of wave B.

A device called oscillator is used to send waves along a stretched string. The string is 20 cm long, and four complete waves fit along its length when the oscillator vibrates 30 times per second. For the waves on the strings.

(a) what is their wavelength?
(b) what is their frequency
(c) what is their speed?

A sound producing body is at considerable distance from a man. There can be four different media W, X, Y and Z between the sound producing body and the man. The medium X brings the sound to man most quickly whereas medium Z takes the maximum time. The time taken by medium W in bringing sound to man is less than that of X but more than that of Z. The medium Y, however, fails to bring the sound from the sound producing body to the man. Which medium could be the one :
(a) having on fixed shape and no fixed volume?
(b) having a fixed volume but no fixed shape?
(c) having the same composition as that on the moon?
(d) having a fixed shape and a fixed volume?

Which of the following vibrates when a musical note is produced by the cymbals in an orchestra?

A musical instrument is producing a continuous note. This note cannot be heard by a person having a normal hearing rang. This note must then be passing through.

In the sound wave produced by a vibrating turning fork shown in the diagram, half the wavelength is represented by :

When the pitch of note produced by a harmonium is lowered, then the wavelength of the note : 

Figure X shows a trace of a sound wave produced by a particular tuning fork :

(a) On the graph paper given in Figure Y, draw a trace of the sound wave which has a higher frequency than that shown in figure X.
(b) On the graph paper show in Figure Z, draw a trace of the sound wave which has a larger amplitude than that shown in Figure X.

Which kind of sound is produced in an earthquake before the main shock wave begins ?

A key of mechanical piano is first struck gently and then struck again but much harder this time. In the second case :

Answer the following question.

Who discovered cells, and how?

Answer the following question.

Why is the cell called the structural and functional unit of life?

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.

Suma is swimming in a pond.

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.

A donkey is carrying a load on its back.

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.

A wind-mill is lifting water from a well.

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.

A green plant is carrying out photosynthesis.

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.

An engine is pulling a train.