Explain why objects moving in fluids must have special shapes.
When a body moves in fluid, it experiences a force of friction called a drag force. It fluids, to overcome the frictional force, objects given special shapes. Frictional force can be minimized by changing in shape of the object. The special shape of the body exerts less friction and move easily in the fluid. That’s why objects moving in fluids must have special shapes.
Describe with the help of a diagram an instrument which can be used to detect a charged body.
Sketch larynx and explain its function in your own words.
Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
Make a labelled diagram of a candle flame.
What is metamorphosis? Give examples.
The following Table shows the total power shortage in India from 1991– 1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.
Make sketches of animal and plant cells. State three differences between them.
What is a constellation? Name any two constellations.
Describe the construction of a kaleidoscope.
Complete the crossword with the help of clues given below:
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.
Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
What is a constellation? Name any two constellations.
Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Gurmit wanted to perform Activity 16.8 using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teachers advise?
In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.
Fill in the blanks in the following statements:
(a) To draw water from a well we have to ——— at the rope.
(b) A charged body ———— an uncharged body towards it.
(c) To move a loaded trolley we have to ———— it.
(d) The north pole of a magnet ———— the north pole of another magnet.
Sketch larynx and explain its function in your own words.
Give two examples of each.
(a) Kharif crop
(b) Rabi crop
Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
How is an embryo developed?
Where are chromosomes found in a cell? State their function.