CBSE Class 6 Science Advanced Physics Motion and Measurement of Distances MCQs Set 01

Answer: (c) wheels

Explanation:
1. Early people dragged loads or used animals, which was slow and tiring.
2. The invention of the wheel made carts, cycles, cars and trains possible, so it changed transport completely.

Teacher's Note:
1. Every vehicle you know has wheels in some form.
2. Carts, cars and cycles came after the wheel, not before it.

Answer: (b) 5000 BC

Explanation:
1. Before animals were used, people carried or dragged loads themselves.
2. People began to use animals to pull loads around 5000 BC.

Teacher's Note:
1. Remember: animals around 5000 BC, wagons and sailing vessels later.
2. BC years count backwards, so 5000 BC is earlier than 3000 BC.

Answer: (b) streamlined shape of fish

Explanation:
1. A boat has to move easily through water, so its shape must cut through water smoothly.
2. A fish has exactly such a smooth streamlined body, so boats were made on the pattern of the streamlined shape of fish.
3. A submarine was invented much later, so it cannot be the pattern.

Teacher's Note:
1. Streamlined means smooth and tapering so that water or air flows past easily.
2. Birds are the pattern for aeroplanes, fish for boats.

Answer: (c) Air

Explanation:
1. Aeroplanes fly at speeds of several hundred kilometres per hour.
2. Ships, road vehicles and trains are all slower, so air is the fastest way to travel.

Teacher's Note:
1. Compare typical speeds: ship, car, train, aeroplane.
2. Air travel also has no roads or tracks to follow.

Answer: (a) The Wright Brothers

Explanation:
1. The first successful powered aeroplane was flown by Orville and Wilbur Wright.
2. Graham Bell invented the telephone, James Watt improved the steam engine and Newcomen made the first steam engine.
3. So the answer is the Wright Brothers.

Teacher's Note:
1. Link each inventor to one invention.
2. The Wright brothers flew their aeroplane in 1903.

Answer: (c) International System of Units.

Explanation:
1. SI comes from the French name Système International d'Unités.
2. In English this is the International System of Units.

Teacher's Note:
1. SI is a worldwide agreed set of units, so scientists can compare results.
2. It is not linked to India in any way.

Answer: (a) kilogram

Explanation:
1. In the SI system the base unit of mass is the kilogram (kg).
2. Centigram, milligram and tonne are other units but are not the SI unit.

Teacher's Note:
1. SI units of length, mass and time are metre, kilogram and second.
2. Gram is the CGS unit, not the SI unit.

Answer: (a) 4.75 km

Explanation:
1. 1 km = 1000 m, so divide the metres by 1000.
2. 4750 ÷ 1000 = 4.75 km.

Teacher's Note:
1. Going from a smaller unit to a larger unit means dividing.
2. Moving the decimal point three places to the left divides by 1000.

Answer: (b) 10,000 centimetre square.

Explanation:
1. 1 m = 100 cm.
2. 1 m² = 100 cm × 100 cm = 10,000 cm².

Teacher's Note:
1. For area, square the conversion factor: (100)² = 10,000.
2. Do not just multiply by 100.

Answer: (c) 10,00,000 cm³

Explanation:
1. 1 m = 100 cm.
2. 1 m³ = 100 × 100 × 100 cm³ = 10,00,000 cm³ (10⁶ cm³).

Teacher's Note:
1. For volume, cube the conversion factor: (100)³ = 10⁶.
2. 10,00,000 is written 1,000,000 in the international style.

Answer: (b) Metre

Explanation:
1. Kelvin is the unit of temperature and ohm is the unit of resistance.
2. Centimetre is a smaller unit of length, not the SI unit.
3. The SI unit of length is the metre.

Teacher's Note:
1. Learn the three base units: metre, kilogram, second.
2. Kelvin and ohm belong to other topics.

Answer: (a) Breadth

Explanation:
1. Area of a rectangle = length × breadth.
2. Volume is a different quantity, and a rectangle has no single 'side'.

Teacher's Note:
1. A rectangle has two different dimensions, length and breadth.
2. For a square both are the same side.

Answer: (a) 1/10 m

Explanation:
1. Deci means one-tenth.
2. 10 dm = 1 m, so 1 dm = 1/10 m.

Teacher's Note:
1. Remember 10 mm = 1 cm, 10 cm = 1 dm, 10 dm = 1 m.
2. 1/100 m is 1 cm.

Answer: (a) 10⁻⁶

Explanation:
1. 1 cm = 1/100 m = 10⁻² m.
2. 1 cm³ = (10⁻² m)³ = 10⁻⁶ m³.

Teacher's Note:
1. Cube the factor: (10⁻²)³ = 10⁻⁶.
2. A cm³ is a very small volume compared with a m³.

Answer: (d) 1 cm, 1 dm, 1 m, 1 dam

Explanation:
1. Convert to metres: 1 cm = 0.01 m, 1 dm = 0.1 m, 1 m = 1 m, 1 dam = 10 m.
2. In increasing order this is 1 cm, 1 dm, 1 m, 1 dam, which is option (d).

Teacher's Note:
1. Change every unit to the same unit before comparing.
2. Ascending means smallest first.

Answer: (a) Rest

Explanation:
1. If the position does not change with time, the body is at rest.
2. The other three words all describe changes of position.

Teacher's Note:
1. Rest and motion are defined using the surroundings.
2. No change of position means rest.

Answer: (a) the bus is in motion.

Explanation:
1. With respect to the ground the bus changes its position, so the bus is in motion.
2. The man standing on the ground does not change his position, so he is at rest.
3. So the correct statement is that the bus is in motion.

Teacher's Note:
1. Always say 'with respect to what' when you talk of motion.
2. A bus passing a standing man is moving; the man is not moving with respect to the road.

Answer: (c) periodic motion.

Explanation:
1. The moon goes round the earth along a closed path and returns to the same position after a fixed time.
2. A motion that repeats after equal intervals of time is periodic motion.
3. The path is curved, not straight, and the moon does not move to and fro, so (b) and (d) are wrong.

Teacher's Note:
1. Periodic motion repeats after a fixed time.
2. Its path is a closed curve and it repeats, so it is not rectilinear.

Answer: (b) path covered by an object between two points

Explanation:
1. Distance is the actual length of the path travelled by a body.
2. It can be longer than the straight line between the two points, so (a) is wrong.
3. The correct choice is (b).

Teacher's Note:
1. Distance depends on the path taken, not just the two end points.
2. Distance is never the product of length and time.

Answer: (b) m/s

Explanation:
1. Speed = distance ÷ time.
2. The SI unit of distance is m and of time is s, so the unit is m/s.
3. m/s² is the unit of acceleration.

Teacher's Note:
1. Always divide the unit of distance by the unit of time.
2. 'ms' would mean metre multiplied by second, which is wrong.

Answer: (a) Speed

Explanation:
1. The dial of a speedometer shows how fast a vehicle is moving, in km/h.
2. It measures speed. The odometer is the instrument that measures the distance.

Teacher's Note:
1. Speedometer shows speed; odometer shows distance covered.
2. Do not mix up the two instruments.

Answer: (d) Oscillatory

Explanation:
1. A pendulum swings to and fro about its mean position.
2. This repeated to-and-fro motion is oscillatory motion.

Teacher's Note:
1. Swing, pendulum, spring: all oscillate.
2. It repeats after a fixed time, so it is also periodic.

Answer: (a) Linear

Explanation:
1. A dropped stone falls straight down along a straight line.
2. Motion along a straight line is linear motion.

Teacher's Note:
1. Falling objects move in a straight line towards the ground.
2. The speed of the stone changes, but the path is still straight.

Answer: (b) Circular

Explanation:
1. A point on a fan blade goes round the fixed axle at a constant distance from it.
2. Its path is a circle, so the motion is circular.

Teacher's Note:
1. Follow one dot on the blade: it traces a circle.
2. Tip of a clock hand moves in the same way.

Answer: (a) Periodic

Explanation:
1. This is the definition of periodic motion.
2. Rotational and vibrational are particular kinds, so 'periodic' is the general answer.

Teacher's Note:
1. The time taken for one repeat is called the time period.
2. Circular and oscillatory motions are both periodic.

Answer: (a) Thomas Newcomen

Explanation:
1. The first practical steam engine was built by Thomas Newcomen in the early 1700s.
2. James Watt later improved it, so the answer is Thomas Newcomen.

Teacher's Note:
1. Newcomen built the first, Watt improved it.
2. Bell and Wright are linked with the telephone and aeroplane.

Answer: (d) an unknown quantity with some known quantity of same kind.

Explanation:
1. To measure a quantity we compare it with a standard quantity of the same kind, called a unit.
2. For example, a length is compared with a metre. So the answer is (d).

Teacher's Note:
1. You cannot measure length with a kilogram; the unit must be of the same kind.
2. The known quantity is the unit.

Answer: (c) 1 second

Explanation:
1. An ordinary wrist watch has a second hand, which moves in steps of 1 second.
2. It cannot show a millisecond, so the smallest time is 1 second.

Teacher's Note:
1. The smallest reading of an instrument is its least count.
2. A stop watch can read smaller times.

Answer: (b) Car is in motion

Explanation:
1. The distance of the car from the pole (a fixed object) keeps changing.
2. A change of position with respect to the surroundings means that the car is in motion.

Teacher's Note:
1. Use a fixed object like a pole as the reference.
2. If the distance does not change, the car is at rest relative to the pole.

Answer: (b) random motion.

Explanation:
1. A kite keeps changing its direction in an unpredictable way as the wind blows.
2. Motion with no fixed direction or pattern is random motion.

Teacher's Note:
1. Birds, kites and ants show random motion.
2. No fixed path and no fixed time means it is not periodic.

Answer: (c) a striker moving across a carrom board.

Explanation:
1. Translatory (linear) motion is motion along a straight line.
2. A striker pushed across a carrom board moves along a straight line, so (c) is correct.
3. A whirled ball moves in a circle and a swing moves to and fro.

Teacher's Note:
1. At this level translatory motion means motion along a straight line.
2. A path that is curved is not a straight-line path.

Answer: (b) Oscillatory

Explanation:
1. While marching, the arms swing forward and backward again and again.
2. This to-and-fro motion is oscillatory motion.

Teacher's Note:
1. Think of the arms as a pendulum.
2. It repeats regularly, so it is also periodic.

Answer: (a) kilogram

Explanation:
1. The SI unit of mass is the kilogram.
2. Gram and centigram are smaller metric units and the pound is not a metric unit.

Teacher's Note:
1. Use the SI unit when the question says 'SI'.
2. 1 kg = 1000 g.

Answer: (b) 24 m³

Explanation:
1. Volume of a cuboid = l × b × h.
2. Volume = 2 × 3 × 4 = 24 m³.

Teacher's Note:
1. Volume is measured in cubic units (m³), not square units.
2. Check the unit at the end: volume is in m³, area is in m².

Answer: (b) Length

Explanation:
1. These units were based on parts of the body and the distance covered by a step or an outstretched arm.
2. All of them measure distance, so they are units of length.

Teacher's Note:
1. Hand span and cubit also measure length.
2. They were replaced by standard units because bodies differ.

Answer: (b) 0.00001 km

Explanation:
1. 1 km = 1000 m = 1000 × 100 cm = 1,00,000 cm.
2. So 1 cm = 1/100000 km = 0.00001 km.

Teacher's Note:
1. Count the zeros carefully: 1 km has 5 zeros in cm.
2. 0.01 km is 10 m, not 1 cm.

Answer: (b) 12 cm³

Explanation:
1. Level before immersion = 70 cm³ and level after immersion = 82 cm³.
2. Volume of the object = 82 − 70 = 12 cm³.

Teacher's Note:
1. Volume of the solid = rise in water level.
2. Do not give the final reading as the answer.

Answer: (d) 4 g/cm³

Explanation:
1. Density = mass ÷ volume.
2. Density = 36 g ÷ 9 cm³ = 4 g/cm³.

Teacher's Note:
1. Write the formula first and then put in the numbers.
2. This question gives its own volume (9 cm³), so use that value.

Answer: (a) 1/1000000

Explanation:
1. The prefix micro means one millionth.
2. So micro = 1/10,00,000 = 1/1000000 = 10⁻⁶.

Teacher's Note:
1. Milli is 1/1000 and micro is 1/1000000.
2. Count six zeros.

Answer: (c) They can be written in full.

Explanation:
1. A unit symbol is a short agreed form, such as N for newton, so (a) is correct.
2. Symbols stay the same for one or many, such as 5 kg not 5 kgs, so (b) is correct.
3. A symbol is itself a short form of the unit name, so a symbol cannot be 'written in full'; (c) is the incorrect statement.
4. Using only agreed symbols is correct, so (d) is true.

Teacher's Note:
1. Examples: 5 m, 5 kg, 5 s, never 5 ms for metres or 5 kgs.
2. Write 5 kg, not 5 kgs; the symbol stays the same for one or many.