English Medium कक्षा ९ - CBSE Question Bank Solutions for Science

In which of the three media, air, water or iron, does sound travel the fastest at a particular temperature?

Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why?

Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.

A sound wave travels at a speed of 339 m s⁻¹. If its wavelength is 1.5 cm, what is the frequency of the wave? Will it be audible?

A stone is dropped from the top of a tower 500 m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g = 10 m s⁻² and speed of sound = 340 m s⁻¹.

Is displacement a scalar quantity ?

State whether distance is a scalar or a vector quantity.

Under what conditions can a body travel a certain distance and yet its resultant displacement be zero ?

Fill in the following blank with suitable word :

Displacement is a…………………… quantity whereas distance is a………………………….

The displacement of a moving object in a given interval of time is zero. Would the distance travelled by the object also be zero ? Give reason for your answer.

What is the difference between distance travelled  by a body and its displacement ? Explain with the
help of a diagram.

An ant travels a distance of 8 cm from P to Q and then moves a distance of 6 cm at right angles to PQ. Find its resultant displacement.

A body is moving along a circular path of radius R. What will be the distance travelled and displacement of the body when it completes half a revolution ?

If on a round trip you travel 6 km and then arrive back home :

What distance have you travelled ?

If on a round trip you travel 6 km and then arrive back home :

What is your final displacement ?

A body travels a distance of 3 km towards East, then 4 km towards North and finally 9 km towards East.

What is the total distance travelled ?

A body travels a distance of 3 km towards East, then 4 km towards North and finally 9 km towards East.

What is the resultant displacement ?

A boy walks from his classroom to the bookshop along a straight corridor towards North. He covers a distance of 20 m in 25 seconds to reach the bookshop. After buying a book, he travels the same distance in the same time to reach back in the classroom. Find (a) average speed, and (b) average velocity, of the boy.

What is the usual name of the forces which cannot produce motion in a body but only change its shape ?

Name the unbalanced force which slows down a moving bicycle when we stop pedalling it.