CBSE Class 7 Science Advanced Physics Machines and Tools MCQs Set 01

Answer: (a) to and fro

Explanation:
1. While sawing, the hand pushes the saw forward and then pulls it back along the same line.
2. A movement that repeats back and forth along a line is to and fro motion.

Teacher's Note:
1. Sawing is a repeated forward and backward stroke.
2. Do not confuse it with rotation, where a body turns about an axis.

Answer: (b) Fixed jaw

Explanation:
1. A hack-saw has a steel blade with teeth, a metal frame that holds the blade tight, and a handle.
2. Jaws belong to a vice, not to a hack-saw, so fixed jaw is not a part of it.

Teacher's Note:
1. List the parts of each tool in your notebook.
2. Fixed and movable jaws are the parts of a vice.

Answer: (b) tool

Explanation:
1. The collet is the part of a multipurpose tool in which different tools are fixed.
2. So the collet holds a tool such as a drill bit, file or screw driver, not the work piece.

Teacher's Note:
1. A vice holds the work piece, whereas a collet holds the tool.
2. Keep the two ideas apart.

Answer: (d) wooden plank

Explanation:
1. Hard clods of mud on the soil surface stop seeds from sprouting.
2. A wooden plank, dragged over the field by bullocks, crushes these clods.
3. A harrow removes weeds, a seed drill sows seeds and a leveller flattens the soil.

Teacher's Note:
1. Match each agricultural tool with its single main job.
2. Clod breaking belongs to the wooden plank.

Answer: (a) Table

Explanation:
1. A vice is clamped to the edge of a table with a screw, so the table is needed to support the vice and the pipe held in it.
2. A drill bit makes holes, and a hammer drives nails, so they are not needed to hold a pipe for cutting.
3. The answer is table.

Teacher's Note:
1. The vice has to be fixed firmly to something steady.
2. A working table is the base on which a vice is clamped.

Answer: (c) Vice

Explanation:
1. A hack-saw, a tin cutter and a drilling tool all cut or make holes in a material.
2. A vice does not cut anything; it only holds the work piece.

Teacher's Note:
1. Look for the property that three items share.
2. Here the odd one only holds the work.

Answer: (d) None of the above

Explanation:
1. The hack-saw has a steel blade and metal frame.
2. The wooden plough has a metal blade fixed on its pointed end.
3. The tin cutter is made of metal.
4. Each one has a metal part, so the answer is none of the above.

Teacher's Note:
1. Even a wooden plough has a metal blade on it.
2. Check every option before choosing 'none of the above'.

Answer: (a) hold the seeds

Explanation:
1. Seeds are poured into the funnel of a seed drill.
2. From there they pass through the plastic tubes and fall into the grooves, so the funnel holds the seeds.

Teacher's Note:
1. Follow the seeds: funnel, then tubes, then the soil.
2. Weeds are removed by a harrow.

Answer: (a) jaws move closer

Explanation:
1. Turning the screw clockwise pushes the movable jaw towards the fixed jaw.
2. The jaws move closer and the vice tightens on the work piece.

Teacher's Note:
1. Clockwise tightens and anti-clockwise loosens, as with most screws.
2. Only the movable jaw moves; the fixed jaw stays on the table.

Answer: (c) Hack saw

Explanation:
1. The blades of a tin cutter act as jaws, a plier grips with two jaws and a vice has a fixed and a movable jaw.
2. A hack saw has only a frame, a blade and a handle, so it has no jaws.

Teacher's Note:
1. The tin cutter, plier and vice all pinch the material between two parts.
2. A saw works by cutting strokes instead.

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

Explanation:
1. A divider has two pointed arms, so keeping one point fixed and turning the other draws a circle (b).
2. A rectangle (a) and a triangle (c) have straight sides, and a divider alone cannot draw straight lines.
3. So the figures that cannot be drawn are both (a) and (c).

Teacher's Note:
1. A divider draws circles and arcs; a straight edge is needed for lines.
2. Check each option before choosing 'both'.

Answer: (d) hammer

Explanation:
1. A file, a poker and a screw driver can all be fitted in the collet.
2. A hammer is a striking tool with a heavy head and cannot be fixed in the collet.

Teacher's Note:
1. Collet tools are the ones that are turned or pushed against the work.
2. A hammer is used on its own.

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

Explanation:
1. A hack-saw blade does the cutting.
2. The vice holds the small piece firmly while it is cut.
3. A screw driver cannot cut metal, so the answer is both (a) and (b).

Teacher's Note:
1. Cutting a small piece needs both a holder and a cutter.
2. The vice is the holder and the blade is the cutter.

Answer: (c) 180°

Explanation:
1. The handles of a tin cutter are squeezed towards each other.
2. The two forces act along the same line in opposite directions.
3. The angle between two opposite forces is 180°.

Teacher's Note:
1. Forces in exactly opposite directions make an angle of 180°.
2. Draw the two hands pressing the handles inward.

Answer: (a) prevent the escape of moisture, present in the surface of field

Explanation:
1. Ploughing loosens and turns the soil so that the water held in the lower layers stays there.
2. It helps to prevent the escape of moisture from the surface of the field.
3. It does not increase evaporation and does not dry the land.

Teacher's Note:
1. Loose soil holds water better than hard, cracked soil.
2. Ploughing prepares the soil for sowing.

Answer: (a) translatory

Explanation:
1. The bullocks pull the plough forward along straight furrows.
2. Every part of the plough moves along a straight line in the same direction, which is translatory motion.

Teacher's Note:
1. Translatory motion means the body moves from one place to another without turning.
2. A plough does not spin or swing.

Answer: (d) All the above

Explanation:
1. A seed drill sows seeds (a).
2. Four or five small ploughs on its plank make the grooves in which seeds fall (b).
3. It can also drop manure near the roots of the plants (c).
4. All three statements are true, so the answer is all the above.

Teacher's Note:
1. Revise the three uses of a seed drill: sowing, equal spacing and feeding the plants.
2. Read each statement before choosing 'all the above'.

Answer: (a) Harrow

Explanation:
1. The harrow has many sharp metal nails fixed on a wooden strip.
2. When pulled, the nails drag the weeds out, so a harrow is used to remove weeds.

Teacher's Note:
1. A harrow also levels wet soil before transplanting.
2. Learn one main use for each tool.

Answer: (a) to penetrate deep into the soil easily.

Explanation:
1. The pointed end of the wooden plough carries a metal blade fixed with nails.
2. The blade helps the plough penetrate deep into the soil easily.
3. The other uses given are not mentioned as the purpose of the blade.

Teacher's Note:
1. Metal is harder than wood, so it cuts the soil better.
2. Remember the blade's main job: easy digging.

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

Explanation:
1. Ploughs are pulled by a pair of bullocks or by a tractor.
2. A man cannot pull a plough through the soil, so the answer is both (a) and (b).

Teacher's Note:
1. Bullocks are tied to the yoke at the end of the long pole.
2. A tractor does the same job faster.

Answer: (a) Tin cutter

Explanation:
1. A tin cutter is made to cut thin sheets and plates of metal.
2. So a tin cutter is the right tool for metal plates of small thickness.

Teacher's Note:
1. Scissors cut paper and cloth, not metal.
2. The spring in a tin cutter makes the job easier.

Answer: (c) Tin cutter

Explanation:
1. A tin cutter is like scissors, with a strong spring between the handle of one blade and the other blade.
2. The answer is tin cutter.

Teacher's Note:
1. The spring stores energy when the handles are pressed.
2. It opens the blades again after each cut.

Answer: (b) rotatory

Explanation:
1. When the rope is pulled, the pulley turns round the axis passing through its centre.
2. A body turning about a fixed axis has rotatory motion.

Teacher's Note:
1. Wheels, fans and pulleys all show rotatory motion.
2. The axis does not move; the pulley turns about it.

Answer: (b) Divider

Explanation:
1. A divider is used to measure distances and to mark equal lengths.
2. A hammer, a multipurpose tool and a hack-saw do other jobs, so the answer is divider.

Teacher's Note:
1. The two pointed arms are set to a length and compared with a scale.
2. Dividers can also draw circles.

Answer: (d) None of the above

Explanation:
1. The wooden plough has a main plough with a metal blade, a long pole and a handle.
2. Every option is a part of it, so the answer is none of the above.

Teacher's Note:
1. The blade is fixed to the main plough.
2. Three main parts are listed in the notes: main plough, long pole, handle.

Answer: (b) wooden plough

Explanation:
1. A screwdriver, a divider and a hack-saw are workshop tools.
2. A wooden plough is used by farmers in the field, so it is an agricultural tool.

Teacher's Note:
1. Workshop tools repair or make articles.
2. Agricultural tools work on the soil or crops.

Answer: (d) Hammer

Explanation:
1. A poker, a chisel and a screw driver can all be fixed in the collet.
2. A hammer cannot be fixed in a collet.

Teacher's Note:
1. The collet holds small, rod-like tools.
2. A hammer has a heavy head fixed on a handle.

Answer: (c) Wooden plank

Explanation:
1. A divider, hammer and vice are used in a workshop to make or repair things.
2. A wooden plank is used by farmers to break mud clods, so it is an agricultural tool.

Teacher's Note:
1. Decide where the tool is used, in a workshop or in a field.
2. Do not confuse the plank tool with an ordinary plank of wood.

Answer: (a) handle

Explanation:
1. The farmer holds the handle of the plough.
2. By moving it he can turn the plough and raise or lower it, so the handle controls the direction and the depth.

Teacher's Note:
1. The long pole joins the plough to the bullocks.
2. The blade only cuts the soil.

Answer: (b) hack saw blade

Explanation:
1. A steel strip with teeth along one edge is the blade of a hack-saw.
2. So it is called a hack saw blade.

Teacher's Note:
1. The teeth do the cutting.
2. The blade is fixed in the metal frame of the saw.

Answer: (d) 160°

Explanation:
1. At 180° the two arms lie in one straight line, so the divider cannot be used to draw a circle.
2. The arms must stay at an angle of less than 180° to the pivot, so the maximum possible angle among the options is 160°.
3. 90° and 45° are smaller, so they are not the maximum.

Teacher's Note:
1. At 180° the two points are as far apart as they can be and the pivot lies between them.
2. Picture the divider opened flat, with both points on one straight line.

Answer: (b) Drill bit

Explanation:
1. A chisel is used to cut grooves and a poker makes holes in metal.
2. A drill bit drills holes in wooden planks.

Teacher's Note:
1. Match the tool to the job as in the notes.
2. Groove, hole in metal, hole in wood: three different tools.

Answer: (c) The vice has only one movable jaw.

Explanation:
1. A vice is tightened by a clockwise turn and loosened by an anti-clockwise turn, so statements (a) and (b) are wrong.
2. It has one fixed jaw and one movable jaw, so statement (c) is correct.

Teacher's Note:
1. First recall the direction rule, then check the jaws.
2. Read all four options before you answer.

Answer: (d) less than 90°

Explanation:
1. The force pulls the plough forward along the beam, while the blade moves in the soil.
2. If this angle were 90° or more, the plough would be difficult to pull, so it is always an acute angle, less than 90°.

Teacher's Note:
1. An acute angle is smaller than 90°.
2. The exact angle depends on the plough and is not 60° always.

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

Explanation:
1. The handle lets the farmer steer the plough, so (a) is correct.
2. It also lets him control the depth of ploughing, so (c) is correct.
3. The bulls are guided by other means, so (b) is wrong.
4. The answer is both (a) and (c).

Teacher's Note:
1. Direction and depth are controlled from the handle.
2. Bullocks are guided by the farmer's voice and rope.

Answer: (c) Leveller

Explanation:
1. A leveller has a heavy frame with a metal strip at the bottom that flattens the soil as it is pulled.
2. The answer is leveller.

Teacher's Note:
1. The name tells you its job.
2. A harrow levels only wet soil before transplanting and mainly removes weeds.

Answer: (d) Seed drill

Explanation:
1. A hammer, a tin cutter and a scale are used in workshops.
2. A seed drill sows seeds in the field, so it is an agricultural tool.

Teacher's Note:
1. Think about where each tool is used.
2. A seed drill is pulled by bullocks or a tractor.

Answer: (a) Seed-drill

Explanation:
1. A seed drill drops seeds through its funnel and tubes into the soil at equal distances.
2. A plough only opens the soil and a harrow removes weeds.
3. The answer is seed-drill.

Teacher's Note:
1. Seed drills keep the rows evenly spaced.
2. They can also drop fertilizer near the roots.

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

Explanation:
1. Statement (a) is true, because different tools fitted in the collet do different jobs.
2. Statement (b) is false, because a drill bit can be fixed to drill holes.
3. Statement (c) is true, because a carpenter's hand saw can be fixed to cut wood.
4. So the answer is both (a) and (c).

Teacher's Note:
1. Check each statement separately.
2. The collet is what makes the tool multipurpose.

Answer: (c) Tractor

Explanation:
1. A bullock cart and a plough are old simple tools.
2. A tractor is a modern machine that can pull ploughs, levellers and seed drills, so it performs many tasks.

Teacher's Note:
1. A tractor replaces bullocks in modern farming.
2. A computer is not an agricultural machine.

Answer: (a) to and fro

Explanation:
1. Depending on how hard the soil is, the farmer lifts the handle up and presses it down.
2. This repeated up-and-down movement is to and fro motion.

Teacher's Note:
1. Think of what the farmer's hands do on the handle.
2. To and fro includes up and down movement.