Motion and Measurement of Distances Class 6 Notes

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Motion is the change in position of an object with respect to time. The movement of a body or an object from one place to another is known as motion. Different objects show varying types of motion. Motion can be classified into three types namely Rectilinear Motion, Circular Motion, and Periodic Motion. The path covered during the motion is known as distance

The object used to move from one place to another is known as the means of transport. The modes of transport we see or use today have a long history of evolution and milestones. The means of transport used by us today are a result of many milestones. The various means of transport are Roadways, Railways, Waterways, and Airways. Measurement is another aspect that has changed over the years. The system used today for measurement is referred to as The International System of Units (SI Units).

Read More: NCERT Solutions for Class 6 Science Motion and Measurement of Distances

Key Terms: Motion, Distance, SI Unit, Rectilinear Motion, Measurement, Unit of Measurement, Circular Motion, Time, Periodic Motion


What is Motion?

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Motion is the movement of an object or a thing or a force that leads or causes that motion. Motion can be defined as the change of the place or location of an object or thing with time. Anything that changes its position with time is known to be in motion. A man walking, water flowing in the river, a pencil falling from the table, etc are all examples of motion.

Motion 

Motion 

The study of motion is important in one’s day-to-day life and, some terms that help describe motion are

  1. Distance
  2. Speed
  3. Time
  4. Displacement

Also Read:


Types of Motion

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All the objects or bodies do not move in the same way. Every object has its way of moving, like bicycle tires moving round and round, but the bicycle moves straight along the road, and the pendulum of a clock moves clockwise.

There are three types of motion:

  1. Rectilinear Motion
  2. Circular Motion
  3. Periodic Motion

Rectilinear Motion

  • When an object or body moves along a straight line in a given time, it is defined as rectilinear motion.
  • Example: A car moving on a road, fruit falling from a tree, a pencil rolling on the table.

Circular Motion

  • When an object or body moves in a circular path, it is known as circular motion but may or may not change the distance to time.
  • Example: Movement of a blade of the fan, the motion of the spinning top.

Read More: Uniform Circular Motion

Periodic Motion

  • A motion that leads to repletion within an interval of time is known as periodic motion. It can also be defined as if the object moves to and fro is known as periodic motion.
  • Example: Pendulum of the clock, motion of a swing.

Read More: Oscillations


Distance

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Distance is defined as the path which is being covered while moving from one place to another. It is the measure of the path which is being covered or how far or long the object or thing is. The length of the cloth, the path covered from Delhi to Chandigarh, the length of the stadium, etc, are all examples of distance.

Displacement is the shortest distance between two places. It is also defined as the change in the position of the object. Displacement can be zero, but distance cannot be zero if there is motion.

Read More: Unit of Displacement


Means of Transport

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In earlier times, people used to travel from one place to another by walking because there was no means of transport. With the evolution of humans, there were various ways and means and different routes for transport like water and roads.

  • With the invention of the wheel, the mode of transportation became easier.
  • Since ancient times people have been using different means of transport for traveling from one place to another.
  • Different types of boats are used for traveling in water bodies. Animal-driven carts, vehicles, and automobiles are used for traveling in rods.

The various mode of transport are as follows:

Road Ways 

  • The first means of transport that were used by man were carts and carriages. 
  • Cars and buses came into existence much later. 
  • The first car with internal combustion was invented in 1906, which is now the basis of many trains and cars. 

Railways 

  • Trains as a means of transport are just 500 years old.
  • Iron was used in railways in the 18th century. 
  • Steam run trains were used as means of long-distance traveling after the invention of steam engines in 1820.
  • Electric trains and monorails knocked on the doors of rail transportation in the 19th century. 
  • Super fast Bullet train is the most modern form of traveling long distances. 

Waterways 

  • Initially wooden logs were used as ways of crossing rivers and lakes. 
  • The wooden logs were cut into plates to form boats in later years. 
  • Boats are still the easiest way of transportation across lakes and ponds. 
  • The larger means of transport in the water like ships and motorboats replaced boats with the invention of motors and engines

Airways 

  • Hot air balloons and gliders were used as means of air transport. 
  • In 1903, humans actually flew whose credit goes to the famous Wright brothers. 
  • Until the 21st century, airways were used only for military purposes. 
  • The modern airplanes and helicopters came into existence for various human transportation uses in the 21st century only. 

Read More: History of Transportation


Measurement 

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Various traditional methods were used to measure distance and length. In ancient times, people used a length of a foot, the width of a finger, and distances of footsteps to measure distance and also as different units of measurement.

  • The people who sell flowers use their forearms as a unit of measurement for making garlands even today and it is an example of measurement of length of the garland.
  • Every person has different sizes of body parts so there was confusion in measurement which was the reason the metric system was introduced.
  • The changing sizes with changing bodies hindered the accuracy of these measurements. 
  • Thus, a standard form of measurement was eventually discovered, which is universally used and accepted today.

Units of Measuring Length in Olden Days

Units of Measuring Length in Olden Days

Read More: Uncertainty in Measurement


Standard Unit of Measurement

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To break the confusion of measurement, the French introduced a common standard unit of measurement, which is used all over the world.

  • The standard unit of measurement is called the international systems of unit ( S.I. Unit). The S.I. Unit of length is a meter.
  • Each meter (m) is divided into 100 centimeters (cm) which is a C.G.S unit.
  • For measuring distances that are very large kilometers are used that is, 1 km = 1000 meters.
  • The various units for measuring length are cm, m, km, mm, etc.

These metric units are related in the following ways: 

1cm = 10 mm 

1m = 100 cm 

1km= 1000 m

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Zero Error and Correct Way to Measure Length

The correct way to measure the length is:

  • Place the scale in contact with the object or thing, which is to be measured.
  • The position of the eye should be correct to take proper measurements and avoid parallax errors.
  • The zero mark on the scale should be properly visible. If the zero mark is not visible, the measurement from that scale should be avoided.
  • The scale should be properly placed to measure correctly.

Errors in Measurement

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There can be various times when the measurement goes wrong because of various reasons like the wrong placement of the scale, or wrong eye position which leads to parallax error.

Parallax Error

Parallax is the change in the original position of the object or thing when it is viewed from a different point or a different position. If such an error occurs while measuring is known as a parallax error.

Parallax Error

Parallax Error

Read More: Measurement of Mass and Weight

How to Measure a Curved Line?

We cannot use meter scales to measure curved lines. So, We use thread to measure the length of curved lines.

  • A knot is created at one end, and it is used as a starting point to measure the curved path or line.
  • Stretch the thread till the whole curved path is covered, and then mark it on the thread.
  • Measure the length from the beginning and the final mark on the thread with the help of a meter scale.

Time

Time is defined as the unit which is used to measure the distance it covers in that period. Distance is measured, with respect to time.

D = S x T

Where

  • D = Distance covered.
  • t = Time taken to cover the distance.
  • s = Speed in which the object or body is moving.

Read More: Unit of Time


Things to Remember

  • The movement of any object with respect to time is known as motion.
  • The path covered by an object is known as distance.
  • Motion in a straight line is called rectilinear motion, while motion in circular paths is known as circular motion.
  • Different means of transport are used to travel from one place to another.
  • In earlier times, people used to measure through their feet, fingers, forearms, etc. which lead to confusion.
  • The SI unit of measurement was introduced by the French to break the confusion all over the world and is used today worldwide.

Sample Questions

Ques. What is motion? (3 Marks)

Ans. The movement of an object or body from one place to another is known as motion. It can be also defined as the change of position of an object or body concerning time. For example, A man walking on the road, a balloon flying in the air, and a dog walking on the road, are all examples of motion. Motion can be of various types such as Rectilinear Motion, Circular Motion, and Periodic Motion.

Ques. What do you mean by rest? (3 Marks)

Ans. A body is said to be at rest if it does not change its position with respect to time. The objects that remain stationary at a place and no change is observed in their position are said to be at rest. For example, a table and chairs lying in a room are in a state of rest, because they do not change their position with respect to the surroundings of the room.

Ques. What is Translatory motion? Give examples. (3 Marks)

Ans. Translatory motion is the motion in which all the particles of a body move through the same distance at the same time. Examples of translatory motion include

  • A car moving along a road or track.
  • Firing of a bullet from a gun.
  • An apple falling from a tree.
  • A ball rolling on the ground.
  • A stone shot from a catapult.

Ques. What are the measures to reduce the parallax error? (3 Marks)

Ans. The parallax error can be reduced with the help of the following measures: 

  • Proper orientation of the eye in a straight line.
  • A fine-edged device must be used. 
  • Average of readings taken.
  • Read lower meniscus for colorless liquids.

Ques. Give two examples of modes of transportation on land and water. (2 Marks)

Ans. The examples are as follows: 

  • Mode of Transport on Land: Car, Bullock Carts, Buses
  • Mode of Transport in Water: Ships, Boats, Submarines

Ques. What is the standard unit of measurement? What to use to measure a curved path? (3 Marks)

Ans. The standard unit of measurement is the International System of Units (SI Units). The basic units of this system are millimeter (mm), centimeter (cm), meter (m), and kilometer (km).

A string or thread is used to measure the curved path by first marking the final ending and measuring it by placing it near the metric scale.

Ques. What is a parallax error? (1 Mark)

Ans. The displacement in the position of an object or body due to the different points of viewing the object is known as parallax, and the error caused during the measurement is called parallax error.

Ques. What are the types of motion? (3 Marks)

Ans. There are three types of motion: 

  • Rectilinear Motion: Any object or body moving in a straight line concerning time is known as rectilinear motion. Examples include a car moving along the road, and a boy running in the park.
  • Circular Motion: When the objects follow a circular path of motion without changing their position, they are in a circular motion. For example, a ferry wheel. 
  • Periodic Motion: It is the kind of motion that repeats after a specific period of time. Examples are the motion of the earth around the Sun and the motion of the moon around the earth.

Ques. If the height of a person is 1.25 m. Express it in cm and mm. (2 Marks)

Ans. The height of the person is given as 1.25 m.

  • Converting in cm: 1.25 x 100 = 125 cm
  • Converting in mm: 125 cm x 10 = 1250 mm

Ques. Give two examples of periodic motion. (1 Mark)

Ans. Two examples of periodic motion are the pendulum and bell ringing.

Ques. The distance between Shyam's home and his school is 3580 m. Express this distance in km. (2 Marks)

Ans. The distance is given as 3580 m.

1 km = 1000 m

So, 3580 m in km = 3580/1000

= 3.580 km

Ques. Which of the following will be used to measure the length of a handbag? 
A) Centimeter 
B) Pounds
C) Miles 
D) None (3 Marks)

Ans. A) Centimeter

The unit Pounds is used to measure the weight of an object. Miles is too long to measure the length of a handbag. Thus, we are left with the unit centimeter, which is used to measure the length of smaller items.

Ques. The motion of the train and car is 
A) Translatory motion 
B) Rotatory motion 
C) To and fro motion 
D) Spin motion (3 Marks)

Ans. (A) Translatory motion 

Trains and cars usually move along straight tracks and roads. Thus, their motion is mostly translatory motion. Until and unless the track or the road is a perfect circle, the motion is not rotatory or to and fro. Therefore, the motion of trains and cars is translatory motion.


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CBSE X Related Questions

1.
Write the balanced chemical equations for the following reactions. 
(a) Calcium hydroxide + Carbon dioxide \(→\) Calcium carbonate + Water 
(b) Zinc + Silver nitrate \(→\) Zinc nitrate + Silver 
(c) Aluminium + Copper chloride \(→\) Aluminium chloride + Copper 
(d) Barium chloride + Potassium sulphate \(→\) Barium sulphate + Potassium chloride

      2.
      Balance the following chemical equations.
      (a) HNO3 +Ca(OH)2 \(→\) Ca(NO3)2 + H2
      (b) NaOH + H2SO4 \(→\) Na2SO4 + H2
      (c) NaCl + AgNO3 \(→\) AgCl + NaNO3 
      (d) BaCl + H2 SO4 \(→\) BaSO4 + HCl

          3.
          Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s−1.

              4.
              Why does the sky appear dark instead of blue to an astronaut?

                  5.
                  Which of the statements about the reaction below are incorrect?
                  \(\text{ 2PbO(s) + C(s) → 2Pb(s) + C}O_2\text{(g)}\)
                  (a) Lead is getting reduced. 
                  (b) Carbon dioxide is getting oxidized. 
                  (c) Carbon is getting oxidized. 
                  (d) Lead oxide is getting reduced.

                    • (a) and (b)

                    • (a) and (c)

                    • (a), (b) and (c)
                    • all

                    6.
                    State two ways to prevent the rusting of iron.

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