English Medium Class 9 - CBSE Question Bank Solutions for Science

A car starts from rest and moves along the x-axis with constant acceleration 5 ms^–2 for 8 seconds. If it then continues with constant velocity, what distance will the car cover in 12 seconds since it started from the rest?

An object is dropped from rest at a height of 150 m and simultaneously another object is dropped from rest at a height of 100 m. What is the difference in their heights after 2s if both the objects drop with the same accelerations? How does the difference in heights vary with time?

Using the following data, draw time - displacement graph for a moving object:

Use this graph to find average velocity for the first 4 s, for the next 4 s and for the last 6 s.

Obtain a relation for the distance travelled by an object moving with uniform acceleration in the interval between 4th and 5th seconds.

An object is put one by one in three liquids having different densities. The object floats with `1/9, 2/11` and `3/7` parts of their volumes outside the liquid surface in liquids of densities d₁, d₂ and d₃ respectively. Which of the following statement is correct?

Establish the relationship between the speed of sound, its wavelength and frequency. If the velocity of sound in air is 340 m s^–1, calculate

(i) wavelength when the frequency is 256 Hz.

(ii) frequency when the wavelength is 0.85 m

Discuss various methods for weed control.

Take an earthen pot (mutka), some pebbles and sand. Design a small-scale filtration plant that you could use to clean muddy water.

Explain the following giving an example.

Colloid

Which of the following will show the “Tyndall effect”?

1. Salt solution
2. Milk
3. Copper sulphate solution
4. Starch solution

Define the atomic mass unit.

A 0.24 g sample of compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. Calculate the percentage composition of the compound by weight.

On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.

J.J. Thomson proposed that the nucleus of an atom contains only nucleons.

Why are we normally advised to take bland and nourishing food when we are sick?

What is the nature of the distance-time graphs for uniform and non-uniform motion of an object?

What can you say about the motion of an object whose distance-time graph is a straight line parallel to the time axis?

What can you say about the motion of an object if its speed-time graph is a straight line parallel to the time axis?

A driver of a car travelling at 52 km h⁻¹ applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h⁻¹ in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

Given figure shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:

1. Which of the three is travelling the fastest?
2. Are all three ever at the same point on the road?
3. How far has C travelled when B passes A?
4. How far has B travelled by the time it passes C?