English Medium Class 9 - CBSE Question Bank Solutions

Salt can be recovered from its solution by evaporation. Suggest some other technique for the same?

Name the process associated with the following

An acetone bottle is left open and the bottle becomes empty.

Give an example of each mixture having the following characteristics. Suggest a suitable method to separate the components of this mixture

A volatile and a non-volatile component.

A rocket is moving up with a velocity v. If the velocity of this rocket is suddenly tripled, what will be the ratio of two kinetic energies?

Avinash can run with a speed of 8 m s^–1 against the frictional force of 10 N, and Kapil can move with a speed of 3 m s^–1 against the frictional force of 25 N. Who is more powerful and why?

A boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km he forgot the correct path at a roundabout (Fig. 11.1) of radius 100 m. However, he moves on the circular path for one and half-cycle and then he moves forward up to 2.0 km. Calculate the work done by him.

Can any object have mechanical energy even if its momentum is zero? Explain.

Can any object have momentum even if its mechanical energy is zero? Explain

The power of a motor pump is 2 kW. How much water per. the minute the pump can raise to a height of 10 m? (Given g = 10m s⁻²)

The velocity of a body moving in a straight line is increased by applying a constant force F, for some distance in the direction of the motion. Prove that the increase in the kinetic energy of the body is equal to the work done by the force on the body.

Is it possible that an object is in a state of accelerated motion due to external force acting on it, but no work is being done by the force? Explain it with an example.

If an electric iron of 1200 W is used for 30 minutes every day, find electric energy consumed in the month of April.

A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has larger kinetic energy?

Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it.

(a) How much work is done by the men in lifting the box?

(b) How much work do they do in just holding it?

(c) Why do they get tired while holding it? (g = 10 m s^–2)

Define watt. Express kilowatt in terms of joule per second. A 150 kg car engine develops 500 W for each kg. What force does it exert in moving the car at a speed of 20 ms^–1?

Which one of the following causes kala-azar?

Why does a desert cooler cool better on a hot dry day?

How does water kept in an earthen pot (matka) become cool during summer?

Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Why are we able to sip hot tea or milk faster from a saucer than a cup?