Short Questions: Motion and Measurement of Distances | NCERT Summary: UPSC PDF Download

Q1: Who created the metric system and why?
Ans: In 1790, the French devised the metric system in order to establish a uniform system of measurement. Until then, different people employed various methods. For example, to measure distance, cubits, paces, foot, yards, and other units were used. There was no uniformity in measurement because each item had a different value. Furthermore, the value of each would vary depending on who was measuring. As a result, to assure homogeneity of measurements throughout different countries, regardless of their size and French introduced the metric system to the world.

Q2: Keith requires 5.6 yards of cloth to get a suit stitched. What length of cloth does he require in metres if 1 yard is 0.9 metres?
Ans: To convert yards to meters, you can use the conversion factor:
1 yard = 0.9 meters
So, to find out how many meters of cloth Keith requires for his suit, you can multiply the yards by the conversion factor:
Length in meters = Length in yards × Conversion factor
Length in meters = 5.6 yards × 0.9 meters/yard
Length in meters = 5.04 meters
Therefore, Keith requires 5.04 meters of cloth to get a suit stitched.

Q3: What were some of the early units of measurement of distances?
Ans: A few of the units of measure were:

• Foot: The foot was based on the length of a human foot. It varied in size between different cultures. For example, the Roman foot was around 29.6 cm.
• Inch: The inch was commonly used for smaller measurements and was often defined as the width of a thumb or the first joint of an adult index finger.
• Cubit: The cubit was the length from the tip of the middle finger to the elbow. It was often used for measuring larger objects like furniture or building materials.
• Handspan: This was the width of a hand, from the tip of the thumb to the tip of the little finger when the hand is fully spread.
• Pace: The pace was the distance covered by a person taking a step. It was often used to measure distances while walking.
• Fathom: The fathom was the distance between a person's outstretched arms. It was commonly used for measuring the depth of water.
• Yard: The yard was often defined as the distance from the nose to the tip of an outstretched arm. It was used for measuring longer distances.
• League: The league was used to describe longer distances, especially at sea. It was approximately three miles.
• Rod or Perch: These were used for measuring land and were often around 5.5 yards in length.
• Ell: The ell was used for measuring textiles, particularly cloth. It varied in size depending on the region.

These units of measurement were based on everyday objects and body parts, making them easy to understand and use in daily life. However, over time, standardized measurement systems were developed to ensure consistency and accuracy in measurements across different regions and cultures.

Q4: The distance from Meena’s house to the playground is 20 paces. If one pace is equal to 40cm, what is the distance in SI units?
Ans: Given that one pace is equal to 40 cm, and the distance from Meena's house to the playground is 20 paces, you can calculate the distance in SI units (meters) by converting the paces to centimeters and then converting centimeters to meters.
1 pace = 40 cm
Distance = 20 paces × 40 cm/pace
Distance = 800 cm
Now, to convert centimeters to meters, you divide by 100 (since there are 100 centimeters in 1 meter):
Distance in meters = 800 cm / 100
Distance in meters = 8 meters
So, the distance from Meena's house to the playground is 8 meters in SI units.

Q5: The length of the blackboard in Ajay’s class is 4.5 cubit. What is its length in SI units if  1cubit = 45.72cm?
Ans: To convert the length of the blackboard from cubits to SI units (centimeters), you can use the conversion factor given:
1 cubit = 45.72 cm
Given that the length of the blackboard is 4.5 cubits, you can multiply this value by the conversion factor to get the length in centimeters:
Length in cm = 4.5 cubits * 45.72 cm/cubit
Calculating this:
Length in cm = 205.74 cm
So, the length of the blackboard in SI units is 205.74 centimeters.