CBSE Class 6 Science Advanced Physics Motion and Measurement of Distances Very Short Answer Questions Set 02

Very Short Answer Type

Question 1. Define distance along with its SI unit.
Answer:
Distance is the actual length of the path travelled by a body. Its SI unit is the metre (m).
In simple words: Distance is how long the path travelled is, measured in metres.

Teacher's Note:
1. It depends on the path taken between two places.
2. It is never negative.

Question 2. Define speed along with its formula and SI unit.
Answer:
Speed is the distance travelled by a body in unit time.
Speed = distance ÷ time, or \( s = \frac{d}{t} \).
Its SI unit is m/s.
In simple words: Speed tells how much distance is covered every second.

Teacher's Note:
1. Write what d, t and s stand for.
2. Other common unit: km/h.

Question 3. Give two examples of modes of transport on land.
Answer:
Two examples are a bullock cart and a car (also bicycle, bus, train).
In simple words: Anything that carries us over the ground is land transport.

Teacher's Note:
1. Name two that you have used yourself.
2. Trains run on tracks and buses on roads.

Question 4. Give two examples of modes of transport in air.
Answer:
Two examples are an aeroplane and a helicopter (also hot-air balloon).
In simple words: Anything that flies carries us through the air.

Teacher's Note:
1. Air travel is the fastest.
2. A rocket travels through air and space.

Question 5. Give two examples of modes of transport on water.
Answer:
Two examples are a boat and a ship (also a raft, canoe or steamer).
In simple words: Anything that floats and carries us is water transport.

Teacher's Note:
1. Rafts and canoes were the earliest water vehicles.
2. Submarines travel under water.

Question 6. Three scales A, B and C are shown in the figure. You have to measure a length of 10 cm. Which scale will you use for a correct measurement?
Which scale will you use?
Answer:
Scale C.
Scale A is broken at the 0 end, so its zero mark is missing and its first mark is 3 cm.
Scale B is cut in the middle, so the part around 2 cm is missing.
Scale C starts with a clear 0 mark and has all the marks up to 13 cm, so 10 cm can be measured from its 0 mark without any error.
In simple words: Choose the ruler that has a clean zero end and no missing marks.

Teacher's Note:
1. Check the zero end first.
2. If the end is damaged, start from another clear mark, but here scale C needs no such trick.

Question 7. 500 m = ____________ km
Answer:
1 km = 1000 m, so divide by 1000.
500 m = 500 ÷ 1000 = 0.5 km.
In simple words: Half a kilometre is 500 metres.

Teacher's Note:
1. Smaller unit to larger unit: divide.
2. Check: 0.5 km is half of 1000 m.

Question 8. Arrange the following lengths in increasing magnitude: 1 metre, 1 centimetre, 1 kilometre, 1 millimetre.
Answer:
In metres: 1 mm = 0.001 m, 1 cm = 0.01 m, 1 m = 1 m, 1 km = 1000 m.
Increasing order: 1 millimetre, 1 centimetre, 1 metre, 1 kilometre.
In simple words: Smallest first: mm, cm, m, km.

Teacher's Note:
1. Convert all to one unit before arranging.
2. Each step is bigger by 10, 100 and 1000.

Question 9. Height of a person is 1.65 m. Express it in cm and mm.
Answer:
1 m = 100 cm, so 1.65 m = 1.65 × 100 = 165 cm.
1 cm = 10 mm, so 165 cm = 165 × 10 = 1650 mm.
In simple words: Multiply by 100 for cm and by 1000 for mm.

Teacher's Note:
1. Going to a smaller unit means a bigger number.
2. 1 m = 1000 mm.

Question 10. Give two examples of periodic motion.
Answer:
Two examples are the motion of a pendulum clock and the motion of the earth around the sun (also tip of a clock hand, a swing).
In simple words: Anything that repeats after equal time gaps is periodic.

Teacher's Note:
1. Mention why: it repeats after fixed time.
2. Both circular and to-and-fro motions are periodic.

Question 11. Correct the following.
(i) The motion of a swing is an example of rectilinear motion.
(ii) The instrument used to measure speed is called as odometer.
Answer:
(i) The motion of a swing is an example of oscillatory (periodic) motion, not rectilinear motion.
(ii) The instrument used to measure speed is called a speedometer. An odometer measures the distance travelled.
In simple words: A swing goes to and fro; the speed meter is the speedometer.

Teacher's Note:
1. Odometer: distance. Speedometer: speed.
2. Rectilinear means a straight line, but a swing follows an arc.

Question 12. What types of motion do the following objects have?
(a) the needle of sewing machine
(b) the smoke from an incense stick
(c) wheels of a moving car
Answer:
(a) Oscillatory (periodic) motion: the needle moves up and down again and again.
(b) Random motion: the smoke moves without a fixed direction.
(c) Combined motion: the wheels spin about the axle and move forward along with the car.
In simple words: Up and down repeatedly, wandering, and spinning plus moving forward.

Teacher's Note:
1. Name the pattern for each answer.
2. Combined motion means two types at once.