CBSE Class 6 Science Advanced Physics Motion and Measurement of Distances Short Answer Questions Set 01

Short Answer Type

Teacher's Note:
1. A table makes the comparison easy to mark.
2. Add one example for each side.

Question 2. Why were the primitive modes of transportation made up of wood?
Answer:
Wood was easily available in forests, and it is light and easy to shape with simple tools.
Wood floats on water, so rafts, canoes and boats could be built from it.
People of that time did not know how to extract and shape metals.
In simple words: Wood was easy to find, easy to cut and it floats.

Teacher's Note:
1. Think of what was available to early people.
2. Floating on water was a very important quality.

Question 3. Find the cost of fencing a square park of side 300 m at the rate of Rs. 25 per metre.
Answer:
Fencing goes round the park, so its length is the perimeter of the square.
Perimeter = 4 × side = 4 × 300 = 1200 m.
Cost = 1200 × Rs. 25 = Rs. 30,000.
In simple words: Find the boundary length first and then multiply by the rate.

Teacher's Note:
1. Perimeter of a square = 4 × side.
2. Cost = length × rate per metre.

Question 4. A motorcycle travels a distance of 248 km in 4 hours. What would be the speed of the motorcycle?
Answer:
Speed = distance ÷ time.
Speed = 248 km ÷ 4 h = 62 km/h.
In SI unit: 62 × 1000 ÷ 3600 ≈ 17.2 m/s.
In simple words: The motorcycle covers 62 km every hour.

Teacher's Note:
1. Check by multiplying: 62 × 4 = 248.
2. To convert km/h to m/s multiply by 5/18.

Question 5. A body travels along the path PQR as shown. What is the distance travelled by the body?
What is the distance travelled by the body?
Answer:
The path PQ is 2 m and the path QR is 2 m.
Distance = PQ + QR = 2 m + 2 m = 4 m.
In simple words: Add the lengths of the two parts of the path.

Teacher's Note:
1. Distance is the length of the actual path.
2. Do not use the straight line PR; it is shorter.

Question 6. What are the advantages of modern means of transport?
Answer:
1. They are fast, so long journeys take much less time.
2. They can carry a large number of people and heavy loads at one time.
3. They connect distant and remote places, which helps trade and tourism.
4. They are comfortable and, in many cases, safe and reliable.
5. Perishable goods like fruits and milk reach far-off markets quickly.
In simple words: Modern transport saves time and carries more.

Teacher's Note:
1. Give four or five clear points.
2. Link each point with an example.

Question 7. What are the disadvantages of modern means of transport?
Answer:
1. Vehicles burn fuel and cause air pollution and noise.
2. They add to global warming and use up fuel resources.
3. The number of road accidents increases.
4. Heavy traffic causes jams and wastes time.
5. Building and running them is costly.
In simple words: Speed and comfort come with pollution, accidents and cost.

Teacher's Note:
1. Pollution is the main point to write.
2. Suggest remedies if asked: public transport, cycling.

Question 8. Why can handspan, cubit and footstep not be used as a standard unit?
Answer:
The length of a handspan, cubit or footstep differs from one person to another.
So the same object would give different measurements when measured by different people.
A standard unit must have a fixed value that is the same for all persons and all places, so these cannot be used.
In simple words: Body parts are not of the same size in all people.

Teacher's Note:
1. The word to remember is 'varies from person to person'.
2. A standard unit never changes.

Question 9. State the importance of measurements.
Answer:
1. We need measurement in daily life: shopkeepers weigh goods, tailors measure the body for clothes.
2. It lets us buy and sell fairly and pay the correct amount.
3. It helps us to estimate how long a journey will take.
4. Science, engineering and trade depend on exact measurement.
In simple words: Measurement makes daily life, trade and science exact.

Teacher's Note:
1. Give two daily-life examples.
2. Accuracy is the key word.

Question 10. Discuss the use of divider.
Answer:
A divider is used to measure the distance between two points accurately.
1. Place the two points of the divider exactly on the two ends of the length to be measured.
2. Without disturbing the opening, lift the divider and place its points on the scale.
3. Read the distance between the two points on the ruler.
It is very useful when the ends of the ruler are worn out, or when reading directly is difficult.
In simple words: Open it to the length, then read that opening against a ruler.

Teacher's Note:
1. Do not change the opening while moving the divider.
2. Keep your eye straight above the mark to read.

Question 11. Why could you not use an elastic measuring tape to measure distance?
Answer:
An elastic tape stretches when it is pulled.
The marks move apart, so the same length gives different readings depending on how hard the tape is pulled.
The reading is therefore not accurate or reliable. A measuring tape must not stretch.
In simple words: Stretching changes the markings, so the reading goes wrong.

Teacher's Note:
1. A good measuring tool keeps its scale constant.
2. Use a tape that does not stretch.

Question 12. The distance between Radha's home and her school is 3250 m. Express this distance in km.
Answer:
1 km = 1000 m.
3250 m = 3250 ÷ 1000 km = 3.25 km.
In simple words: Divide by 1000 to convert metres to kilometres.

Teacher's Note:
1. Move the decimal three places left.
2. Check: 3.25 km × 1000 = 3250 m.

Teacher's Note:
1. Draw a small picture if you can.
2. Both types are special cases of periodic motion.