English Medium कक्षा ९ - CBSE Question Bank Solutions for Science

If bromine atom is available in the form of, say, two isotopes `""_35^79Br (49.7%)" and """_35^81Br (50.3%)`, calculate the average atomic mass of bromine atom.

The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes `""_8^16X" and """_8^18X` in the sample?

Name types of simple tissues.

What are the constituents of phloem?

When will you say a body is at non-uniform acceleration?

A bus decreases its speed from 80 km h⁻¹ to 60 km h⁻¹ in 5 s. Find the acceleration of the bus.

A train starting from a railway station and moving with uniform acceleration attains a speed 40 km h⁻¹ in 10 minutes. Find its acceleration.

A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force? Explain your answer.

The potential energy of a freely falling object decreases progressively. Does this violate the law of conservation of energy? Why?

Which of the two can be zero under certain conditions : average speed of a moving body or average velocity of a moving body ?

Give one example of a situation in which a body has a certain average speed but its average velocity is zero.

Name the physical quantity whose SI unit is :
(a) m/s (b) m/s²

Fill in the following blank with suitable word :

A motorcycle has a steady……………. of 3 m/s². This means that every………………. its…………….. increases by………….

Fill in the following blank with suitable word :

Velocity is the rate of change of……………………… It is measured in.............. .

Fill in the following blank with a suitable word:

Acceleration is the rate of change of ______ It is measured in ______

What term is used to denote the change of velocity with time ?

Define velocity. What is the SI unit of velocity ?

What is meant by the term acceleration ? State the SI unit of acceleration.

What conclusion can you draw about the velocity of a body from the displacement-time graph shown below :

Name the quantity which is measured by the area occupied under the velocity-time graph.