CBSE Class 7 Science Advanced Physics Machines and Tools Very Short Answer Questions Set 01

Very Short Answer Questions

Question 1. _______ can be used to remove nails from a wall or a piece of wood.
Answer:
A hammer with a fork.
In simple words: The forked side of the hammer grips a nail and pulls it out.

Teacher's Note:
1. An ordinary hammer only drives nails in.
2. Remember that the fork or claw is the part that removes nails.

Question 2. Tools can not reduce the _______ done by the effort.
Answer:
work
In simple words: A tool makes the job easier but the total work remains the same.

Teacher's Note:
1. Tools reduce the effort we must put in, not the work to be done.
2. This idea is the heart of the introduction to the chapter.

Question 3. The _______ tools should be cleaned and oiled after every use.
Answer:
metal
In simple words: Oiling keeps iron and steel tools from rusting.

Teacher's Note:
1. Wooden tools only need cleaning.
2. Oil or grease makes a thin layer that keeps out moisture.

Question 4. A _____ can be used to level the wet field before transplantation.
Answer:
harrow
In simple words: A harrow smooths wet soil so that young plants can be planted.

Teacher's Note:
1. A harrow has two jobs: removing weeds and levelling wet soil.
2. A leveller flattens dry soil.

Question 5. Tools help us to do work with less _____.
Answer:
effort
In simple words: With a tool we need to push or pull less to finish the same job.

Teacher's Note:
1. Effort is the force or energy that we apply.
2. Do not write 'work' here; the work remains the same.

Question 6. When the screw used to fix the object between the jaws is rotated in the clockwise direction, then the ________ jaw moves towards ________.
Answer:
movable jaw moves towards the fixed jaw.
In simple words: A clockwise turn pushes the movable jaw to the fixed jaw and grips the object.

Teacher's Note:
1. Clockwise means the vice tightens.
2. Only one jaw moves, so the other must be the fixed one.

Question 7. To draw circles on the wood, _______ is used.
Answer:
Dividers (a pair of dividers)
In simple words: One pointed arm stays at the centre and the other scratches the circle.

Teacher's Note:
1. Set the arms apart by the radius you want.
2. Dividers also measure distances.

Question 8. _______ is used to make holes in the metal rods
Answer:
A poker
In simple words: A poker, fitted in the collet of a multipurpose tool, pierces metal.

Teacher's Note:
1. Do not confuse it with a drill bit, which is used for wood.
2. The poker is one of the tools that fits in a collet.

Teacher's Note:
1. Match the sure ones first and leave the doubtful ones to the end.
2. Each answer in Column B is used exactly once.

Question 10. How are wooden tools and metal tools maintained?
Answer:
Wooden tools are cleaned after every use.
Metal tools are oiled or greased at regular intervals to prevent rusting.
In simple words: Wipe the wooden ones clean and oil the metal ones.

Teacher's Note:
1. Say what is done for each kind separately.
2. Rusting is the damage that oil prevents.

Question 11. Name the tool which is used to put fertilizer near the roots of a plant.
Answer:
The seed drill
In simple words: A seed drill can drop manure near the plant roots through its tubes.

Teacher's Note:
1. The seed drill does three jobs: sowing, spacing and feeding.
2. The funnel and tubes carry the material to the soil.

Question 12. What is the use of collet in a multipurpose tool?
Answer:
The collet holds the tool that is fixed in it. Different tools are fitted in the collet depending on the work to be done.
In simple words: It is the holder that grips the tool of your choice.

Teacher's Note:
1. The collet is why the tool is called multipurpose.
2. It holds a tool, not the work piece.

Question 13. Name few tools which can be fixed on a multipurpose tool.
Answer:
Carpenter's hand saw, screw driver, poker, drill bit, file and chisel.
In simple words: Saw, screw driver, poker, drill bit, file and chisel can be fitted.

Teacher's Note:
1. Write at least three tools and mention their use.
2. A hammer cannot be fixed in the collet.

Question 14. What is a tool?
Answer:
A tool is a device that helps us to do a job with less effort. Hammers, scissors, screw drivers and tin cutters are examples.
In simple words: A tool is a helper that makes a job easier.

Teacher's Note:
1. Give an example or two to complete the answer.
2. A tool reduces the effort, not the work done.

Question 15. Write one use of a tin-cutter.
Answer:
A tin-cutter is used to cut thin metal plates or sheets.
In simple words: A tin-cutter is scissors for thin metal.

Teacher's Note:
1. One clear use is enough for this question.
2. Mention that it works on thin sheets, not thick rods.

Question 16. What are the uses of jaws in a vice?
Answer:
The two jaws of a vice hold the work piece firmly between them.
The fixed jaw is attached to the table and the movable jaw is moved by the screw, so the piece is gripped tightly while it is cut, threaded or smoothed.
In simple words: The jaws are the grip that holds the metal while we work on it.

Teacher's Note:
1. Mention that one jaw is fixed and the other is movable.
2. Holding the piece leaves both of the worker's hands free.

Question 17. What are the advantages of using seed drill?
Answer:
1. The distance between two rows of seeds remains the same.
2. The seeds fall at equal distances from one another.
3. Fertilizer or manure can be dropped near the roots of the plants.
4. Seeds are sown quickly and with less effort.
In simple words: A seed drill sows evenly and also feeds the plants.

Teacher's Note:
1. Equal spacing gives every plant enough space to grow.
2. Sowing by hand cannot give such an even spread.

Question 18. Why is oil or grease applied to tools?
Answer:
Oil or grease forms a coating on the metal that keeps out moisture and air, so the tools do not rust.
It also reduces friction between moving parts.
In simple words: A thin film of oil stops iron from rusting.

Teacher's Note:
1. Rust forms when iron touches air and water.
2. Greasing is done at regular intervals.

Question 19. What is the use of the long pole in a wooden plough?
Answer:
One end of the long pole is fixed to the main plough and the other end is tied to the yoke of the bullocks, so the pull of the bullocks is passed on to the plough.
In simple words: The long pole joins the plough to the bullocks.

Teacher's Note:
1. Its length is about 2½ metres.
2. Without it the bullocks could not pull the plough.

Question 20. What are the different kinds of hammers?
Answer:
There are two kinds of hammers.
1. An ordinary hammer, which is used only to fix (drive) nails.
2. A hammer with a fork, which is used to fix nails and also to remove them.
In simple words: One kind only hits nails; the other also pulls them out.

Teacher's Note:
1. Say what each kind can do.
2. The fork is used for removing nails.

Question 21. State whether the following statement is true or false: An ordinary hammer can be used to remove nails from a wall or a piece of wood.
Answer:
False. A hammer with a fork is used to remove nails; an ordinary hammer is used only to fix them.
In simple words: Only the forked hammer can pull nails out.

Teacher's Note:
1. In true-false questions give the reason when you can.
2. Compare the two kinds of hammers.

Question 22. State whether the following statement is true or false: The diameter of a metallic plate can be measured by using a divider.
Answer:
True. The pointed arms of a divider are placed at the two ends of the diameter and the gap is compared with a scale.
In simple words: Open the divider to the width of the plate and read the gap on a ruler.

Teacher's Note:
1. A divider is a measuring tool.
2. Dividers are very useful for hot or rough objects.

Question 23. State whether the following statement is true or false: The hack-saw blade cannot be removed from a hack-saw.
Answer:
False. The blade is fitted to the frame and can be taken out and replaced.
In simple words: A worn blade can be removed and changed.

Teacher's Note:
1. The blade is only held tight in the frame.
2. That is why a new blade can be fitted when the teeth wear out.

Question 24. State whether the following statement is true or false: A harrow can be used to level the wet field before transplantation.
Answer:
True. A harrow removes weeds and also levels the wet field before plants are transplanted.
In simple words: Harrow work is weeding and levelling wet soil.

Teacher's Note:
1. Remember both uses of a harrow.
2. Transplantation means shifting young plants into the field.

Question 25. State whether the following statement is true or false: A hammer is made of a soft metal.
Answer:
False. A hammer is made of a hard and heavy metal so that it does not get damaged when it strikes.
In simple words: A soft metal would dent when striking; a hard heavy metal is needed.

Teacher's Note:
1. Hardness and weight make a hammer effective.
2. A soft head would change shape.