GSEB Class 6 Science Solutions Chapter 10 Motion and Measurement of Distances

Question 1. Give two examples each of the modes of transport used on land, water and air.
Answer:

• Land – Bus, truck, train
• Water – Ship, boat
• Air – Aeroplane, Helicopter

Exam Tip: Remember to give two distinct examples for each category as requested by the question to ensure full marks.

Question 2. Fill in the blanks:
1. One metre is ....... cm.
2. Five kilometres is ....... m.
3. The motion of a child on a swing is ..........
4. The motion of the needle of a sewing machine is ..........
5. The motion of the wheel of a bicycle is ..........
Answer:
1. One metre is 100 cm.
2. Five kilometres is 5000 m.
3. The motion of a child on a swing is periodic (oscillatory) motion.
4. The motion of the needle of a sewing machine is periodic oscillatory.
5. The motion of the wheel of a bicycle is circular.
In simple words: We are filling in the blanks with correct measurements and types of motion. Remember that 1 metre equals 100 centimetres, and 1 kilometre equals 1000 metres. Periodic motion happens when something repeats its movement over and over, like a swing or a sewing machine needle. A bicycle wheel turns in a circle, showing circular motion.

Exam Tip: Understand the basic units of measurement and different types of motion. This will help you answer such fill-in-the-blanks questions accurately.

Question 3. Why can a pace or a footstep not be used as a standard unit of length?
Answer: Because a pace or a footstep of each and every person is not equal. Different people have different stride lengths, meaning the measurement would change depending on who does it. This makes it unreliable for standard measurements.
In simple words: We can't use a pace or footstep as a standard unit of length because everyone's steps are different lengths. So, the measurement would never be the same for everyone.

Exam Tip: When discussing standard units, always emphasize the need for consistency and universal agreement in measurements. Non-standard units like paces vary from person to person, making them unsuitable for exact science.

Question 4. Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre, 1 millimetre.
Answer:
Ascending order of length:
1 millimetre < 1 centimetre < 1 metre < 1 kilometre
In simple words: When we sort the lengths from smallest to largest, millimetre comes first, then centimetre, followed by metre, and finally kilometre is the biggest.

Exam Tip: To arrange units of length, convert them all to a common unit (e.g., millimetres or metres) first to compare them accurately before writing the final ordered list.

Question 5. The height of a person is 1.65 m. Express it in cm and mm.
Answer:
(a) \( 1.65 \text{ m} \), as one metre \( = 100 \text{ cm} \). So, \( 1.65 \times 100 \text{ cm} = 165 \text{ cm} \).
(b) \( 1.65 \text{ m} \), as one metre \( = 100 \text{ cm} \) and one centimetre \( = 10 \text{ mm} \). So, \( 1.65 \times 100 \times 10 \text{ mm} = 1650 \text{ mm} \).
In simple words: To change metres to centimetres, multiply by 100. To change metres to millimetres, multiply by 1000 (since 100 cm x 10 mm/cm = 1000 mm).

Exam Tip: Remember the standard conversions: 1 metre = 100 centimetres and 1 centimetre = 10 millimetres. This allows you to easily convert between these units.

Question 6. The distance between Radha's home and her school is 3250 m. Express this distance in km.
Answer:
As one km \( = 1000 \text{ m} \).
Therefore, \( \frac {3250}{1000} \text{ km} = 3.250 \text{ km} \).
Thus, the distance between Radha's home and her school is \( 3.250 \text{ km} \).
In simple words: To change metres into kilometres, divide the number of metres by 1000.

Exam Tip: Always recall that 1 kilometre equals 1000 metres. When converting from a smaller unit (metres) to a larger unit (kilometres), you divide.

Question 7. While measuring the length of a knitting needle, the reading of the scale at one end is 3.0 cm and at the other end is 33.1 cm. What is the length of the needle?
Answer:
Length of the needle \( = 33.1 \text{ cm} - 3.0 \text{ cm} = 30.1 \text{ cm} \).
In simple words: To find the actual length, just subtract the smaller measurement from the bigger measurement.

Exam Tip: When measuring lengths using a scale where the starting point isn't zero, subtract the initial reading from the final reading to get the actual length of the object.

Question 8. Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
Answer:
1. Similarity: Both the wheel of a bicycle and a ceiling fan exhibit motion on a fixed axis. They both spin around a central point.
2. Dissimilarity: A bicycle moves forward, performing rectilinear motion, while its wheels also rotate. A fan, however, only rotates on its axis and does not move from its place, so it shows only rotating motion.
In simple words: Both a bicycle wheel and a fan spin around a central point. But a bicycle moves straight ahead too, while a fan just stays in one spot and spins.

Exam Tip: When comparing motions, identify common elements (like rotation) and distinct elements (like translation or rectilinear motion) to highlight both similarities and differences.

Question 9. Why could you not like to use a measuring tape made of an elastic material like rubber to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with such a tape?
Answer: An elastic measuring tape gives an incorrect length of the distance between two points because its length changes when stretched.

• The length of the elastic tape varies and depends upon the force by which it is stretched. If you pull it harder, it gets longer.
• Measurement would vary between 2 or 3 readings even when measured by the same person and by the same elastic tape. Each pull would give a slightly different number.
• Measurement would also vary if different persons measure the same distance. Everyone pulls with a different strength, making the results inconsistent.

Exam Tip: Emphasize the importance of fixed, unchangeable standards for accurate measurement. Any tool that can change its own length during use is unsuitable for reliable distance measurement.

Question 10. Give two examples of periodic motion.
Answer:

• Oscillations of a pendulum
• Motion of a swing/motion of Earth around the sun

Exam Tip: Periodic motion is any motion that repeats itself at regular intervals. Think of examples where objects go back and forth or in a regular cycle.