CBSE Class 7 Science Advanced Physics Machines and Tools MCQs Set 02

Answer: (b) A → c; B → d; C → a; D → b

Explanation:
1. A poker is used to make holes in metal sheets: A → c.
2. A funnel is a part of the seed drill that holds the seeds: B → d.
3. A file is used to sharpen knives: C → a.
4. A spring is used in the tin cutter: D → b.
5. This is option (b).

Teacher's Note:
1. Tin cutters open by a spring.
2. The seed drill drops seeds through funnels.

Answer: (b) Jaws move away.

Explanation:
1. Turning the screw of a vice clockwise tightens it and brings the jaws closer.
2. Turning it anticlockwise does the opposite: the jaws move apart.
3. The answer is (b).

Teacher's Note:
1. Clockwise tightens, anticlockwise loosens.
2. The vice itself does not rotate.

Answer: (d) All the above

Explanation:
1. A vice holds the work piece firmly on a table so that it can be cut, filed (smoothened) or threaded.
2. So all the given operations are done on a piece held in a vice: (d).

Teacher's Note:
1. The vice is a holding device used with other tools.
2. It leaves both hands free to work.

Answer: (c) 20

Explanation:
1. Area = width of the strip × length of the field.
2. Length = 30 ÷ 1.5 = 20 m.
3. The answer is 20 m.

Teacher's Note:
1. Divide the area by the width of the leveller.
2. Check: 1.5 × 20 = 30 m².

Answer: (c) 7

Explanation:
1. Thickness = 3.5 cm = 35 mm.
2. Each rotation moves the jaw 5 mm, so rotations = 35 ÷ 5 = 7.
3. The answer is 7.

Teacher's Note:
1. Convert to the same unit first.
2. Divide the distance by the distance per turn.

Answer: (b) Table

Explanation:
1. A vice is fixed to a table or workbench, and the pipe is clamped in it.
2. Of the options, the book picks the table as what is required to fix the vice and cut the pipe.
3. The answer is (b) Table.

Teacher's Note:
1. A vice must be mounted on a firm table.
2. The other tools do not support the vice.

Answer: (a) 30

Explanation:
1. Area levelled = width of the strip × length of the field = 1 m × 30 m.
2. = 30 m²: option (a).

Teacher's Note:
1. Area = width × length.
2. One pass covers a strip 1 m wide.

Answer: (b) 2.5 cm

Explanation:
1. Distance moved by the jaw = number of rotations × distance per rotation.
2. = 5 × 0.5 cm = 2.5 cm.
3. The thickness is 2.5 cm.

Teacher's Note:
1. Multiply turns by the distance per turn.
2. The jaw closes on the plate, so the distance moved equals its thickness.

Answer: (d) Harrow

Explanation:
1. A harrow has long teeth that scrape the soil and uproot weeds.
2. A plough turns the soil, a seed drill sows seeds, and a tin cutter cuts metal sheets.
3. The answer is harrow.

Teacher's Note:
1. The harrow is dragged over the soil after ploughing.
2. It also breaks up clods.

Answer: (b) Harrow

Explanation:
1. Divider, vice and hammer are workshop tools.
2. The harrow is used in the field.
3. The answer is harrow.

Teacher's Note:
1. Agricultural tools: plough, harrow, leveller, seed drill.
2. Workshop tools: vice, hammer, divider.

Answer: (c) A → r; B → s; C → p; D → q

Explanation:
1. A wooden plank breaks the mud rocks (clods) on the soil: A → r.
2. The Earth is flattened at the poles, so g is larger there (9.831 m s⁻²): B → s.
3. A leveller has two rings fixed to a wooden frame: C → p.
4. g at the equator is smaller (9.781 m s⁻²): D → q.
5. This is option (c).

Teacher's Note:
1. The poles are closer to the earth's centre, so g is greater there.
2. Match the tools first, then the g values.

Answer: (c) Tin cutter

Explanation:
1. A tin cutter has a spring between its handles that opens the blades after each cut.
2. The vice, hacksaw and drilling tool do not use a spring.
3. The answer is tin cutter.

Teacher's Note:
1. Think of scissors-like tools that spring back.
2. The spring saves effort for the hand.

Answer: (c) Divider

Explanation:
1. A divider has two pointed legs; one stays at the centre and the other marks the circle.
2. The answer is divider.

Teacher's Note:
1. It works like a compass.
2. A hammer drives nails and a vice holds work.

Answer: (b) Wooden plank, leveller, seed drills

Explanation:
1. The soil is first broken with the wooden plank to crush the mud rocks.
2. Then the leveller makes the field flat.
3. Finally the seed drill sows the seeds.
4. The order is wooden plank, leveller, seed drill: option (b).

Teacher's Note:
1. Prepare the soil first, sow last.
2. Option (a) is incomplete and (d) puts the seed drill first.

Answer: (d) None of these

Explanation:
1. A wooden plough has a handle, a blade (share) and a long pole.
2. All three given parts belong to it, so the answer is (d) None of these.

Teacher's Note:
1. The question asks for a part that does not belong; every option belongs.
2. Read the options carefully.

Answer: (b) Leveller

Explanation:
1. A leveller is dragged over the field to make the surface flat.
2. The answer is leveller.

Teacher's Note:
1. The name tells the job.
2. Wooden planks break clods; they do not level.

Answer: (c) Both (a) and (b)

Explanation:
1. A vice and a hacksaw blade are both used in a workshop.
2. A leveller is a farm tool.
3. The answer is (c) Both (a) and (b).

Teacher's Note:
1. Workshop tools work on metal and wood.
2. The leveller is for the field.

Answer: (b) BAC

Explanation:
1. Place the pipe between the jaws: (B).
2. Turn the screw clockwise to tighten the vice: (A).
3. Cut the pipe with the hacksaw: (C).
4. The order is B, A, C: option (b).

Teacher's Note:
1. The pipe must be in place before it is tightened.
2. Cut only after it is held firmly.

Answer: (b) Vice

Explanation:
1. A vice has two jaws that grip the work piece.
2. A hacksaw and a screwdriver have no jaws.
3. The answer is vice.

Teacher's Note:
1. Jaws are the gripping parts.
2. Only the vice grips with jaws here.

Answer: (a) Wooden plank

Explanation:
1. A wooden plank is dragged over the field and crushes the clods (mud rocks).
2. A seed drill sows seeds, and the book does not use the harrow for this.
3. The answer is wooden plank.

Teacher's Note:
1. Planks flatten and crush clods.
2. The seed drill is for sowing.

Answer: (b) Collet

Explanation:
1. The tin cutter, divider and hammer are tools.
2. A collet is a part of the multipurpose tool that holds the drill bit.
3. So the collet is different: (b).

Teacher's Note:
1. Three are complete tools; one is a part.
2. The collet grips the bit.

Answer: (c) Drill bit

Explanation:
1. The collet of a multipurpose tool holds interchangeable bits.
2. A drill bit is fixed in it.
3. The answer is drill bit.

Teacher's Note:
1. Leveller, seed drill and plough are farm tools.
2. Bits can be changed for different jobs.

Answer: (a) Both A and R are true, and R is the correct explanation of A.

Explanation:
1. A is true: metal tools are oiled or greased regularly.
2. R is true: the oil or grease keeps air and moisture away and prevents rusting.
3. R explains A: (a).

Teacher's Note:
1. Rust needs air and moisture.
2. A thin film of oil blocks both.