Class 06 || Science || Ch. 10. Motion and Measurement of Distances

Class 06 || Science || Ch. 10. Motion and Measurement of Distances

In ancient time man used to move only on foot and carry goods either on his back or on his had. after rearing the some animals on the back of them.

A great change in the modes of transport was made after the:

* invention of wheel.

* invention of steam engine.

Q. What was the main transport in ancient time?

Ans.  Water Transport was main transport in ancient times. For transport along water routes, boats were used. To beginning, boats were simple logs of wood with hollow cavity. 

The people learnt to make a boat later after putting together different pieces of wood and give a special shapes. 

Q. How the invention of wheel made a great change in mode of transport?

Ans. Long ago people did not about the means of transport. They used to move only on foot and carry goods on their heads or back. 

            Invention of the wheel made a great change in modes of transport. The design of the wheel improved over thousands of years. They use the log of woods like a wheel. After rearing the animals he used to pull carts that moved on wheels.

Until the beginning of the 19th

century, people were depended on

animal power to transport from

place to place.

            Now a days many types of the vehicles can see moving on the wheels. We cannot think about this world without wheel .

Q. What type of the change came after the invention of the steam engine?

Ans. The invention of steam engine introduced a new source of power. Railroads were made for steam engine driven carriages and wagons etc. Automobiles, Motorised boats and ships were came later to use as means of transport on water.

The early years of 1900 the aeroplanes developed. These were later improved to carry passengers and goods. 

Electric trains, monorail, supersonic aeroplanes and spacecraft are some of the 20th century contributions.

Q. What do you mean by the means of the transport ?

Ans. The vehicles necessary for transport are called means of transport. The means of transport are of mainly three types– 1. Road Transport (car, bus, truck, rail), 2. Water Transport boat, motor boat, ship) and 3. Air Transport (aeroplane helicopter) and .

Q. What are main types of mode of transportation?

Ans. These are five most common  modes of transport : railways, roadways, airways, waterways and pipelines.

Q. Why did accuracy needed in measuring?

Ans. While measuring things, accuracy is needed. A variety of units can be used for measuring purpose.

This known fixed quantity is called a unit like 5 span, 7 feet and 2 cubit. Here span, 7 feet and 2 cubit are measuring units.

A unit of measurement which has fixed value and which does not change from person to person or place to place, is called standard unit of measurement.

Q. What do you mean by the measurement ? what are its type?

Ans.  Comparison of an unknown quantity with some known fixed quantity of the same kind is known Measurement. 

This fixed known quantity is called a unit like 5 span, 7 feet and 2 cubit. Here span, 7 feet and 2 cubit are measuring units.

Each measurement consists of a number which denote the numerical value of the measure or the unit in which the quantity is measured.

Measurements are of two types (i) Non standard measurement and (ii) Standard measurement

Non-standard measures: vendor methods of measurement very people tree table is known as non standard measure, like that the lengths of foot or steps, arms (cubit), hands (span), or fingers of different people are different, therefore the distance measured with their help is not always reliable. 

These methods are, therefore, called non-standard measures.

Standard measures: Measures that are the same all over the world are known as standard measures.

In October 1960, the 12th general conference on weight and measures adopted the International system of units. “The System International Units” or 'SI Unit's is the set of units to maintain uniformity all over the world.

* In ancient times, the length of a foot (feet), the width of a finger (span), and the distance of a step (furlang) were commonly used as different units of measurements.

Q. What do you mean by cubit?

Ans. A cubit as the length from the elbow to the finger tips was used in ancient Egypt. Later, It was accepted as a unit of length in other parts of the world.

Q. What do you mean by angul or a mutthi ?

Ans. In ancient India, small length measurements used were an angul (finger) or a mutthi (fist). Even today, we can see flower sellers using their forearm as a unit of length for garlands in many towns of India. 

Q. What do you mean by the metric system? when it is accepted?

Ans.  To remove the confusion in measurement the French created a system of standard unit of measurement called the metric system in 1790.

Q. What do you mean by the SI units? 

Ans. The scientists all over the world have accepted a set of uniform standard units of measurement. The system of units now used is known as the International System of Units (SI units). The SI unit of length is a metre.

Q. What is a metre? in how many parts it is divided? Explain.

Ans. Metre: It is the standard unit of length. The symbol of metre is m.

Each metre (m) is divided into 100 equal divisions, called centimetre (cm). Each centimetre has ten equal divisions, called millimetre (mm). Thus

1 m = 100 cm

1 cm = 10 mm

1 m = 10 dm  = 100 cm = 1000 mm

Q. What do you mean by Sub-multiples of units of a metre? 

Ans. Sub-multiples of units: Units used for measuring smaller distances are the sub-multiples of SI units.
For example, milli, centi, deci.

1 m = 10 decimetre
1 m = 100 centimetre
1 m = 1000 millimetre.

1 m = 10 dm  = 100 cm = 1000 mm

Q. What do you mean by Multiples or Simple multiples of units of a metre? why did we use these units?

Ans. Multiples or Simple multiples of units: Units that are used for the measuring bigger or larger distances are the multiples of SI unit are called Multiples or Simple multiples of units . For example: deca, hecto, kilo.

1 decametre   = 10 m
1 hectometre  = 100 m
1 kilometre     = 1000 m

1 km = 10 hm  = 100 dam = 1000 m

Measuring of large distances in metre is not a convenient in unit. So we define a larger unit of length. It is called kilometre (km).
1 km = 1000 m.

Q. What is the correct method of of making measurement of length?

Ans. Making measurement of a length: In making measurement of length of an object, we should follow the following procedure:

Place the scale in contact with the object along its length as shown in Fig.

Measurement with a scale with broken ends

• Avoid taking measurements from zero mark.
• Use any other full mark of the scale, say 1.0 cm.
• Subtract the reading of this mark from the reading at the other end. For example, in Fig. 10.3 (6), the reading at starting mark is 1.0 cm and at the other end it is 6.5 cm. Therefore, the length of the object is (6.5 – 1.0) cm = 5.5 cm.

Correct position of the eye is also important for making measurement. Your eye must be exactly above the point where the measurement is to be taken as shown in Fig. 10.4. Position ‘A’ is the correct position of the eye. Note that from position A’, the reading is 1.0 cm. From positions ‘B’ and ‘C’, the readings may be different.

Q. What do you mean by the least count?

Ans. Least count: A scale is marked in centimetres and millimetres. With the scales of this kind we can measure correctly up to one millimetre, that is one-tenth of a centimetre. This is called the least count of a (15 cm) scale.

To make accurate measurement, we need a proper measuring device.

Q. Write the name of two length-measuring devices ?

Ans. Two commonly used length-measuring devices are:

(a) Ruler or metre scale
(b) Measuring tape

Q. How will you make an accurate measurement with a scale or ruller?

Ans.  While measuring length using a metre scale or a ruler, we must follow the steps carefully given below:

(a) The ruler should be kept along the length of the object so that the zero mark on the ruler coincides with the one end of the object as shown in figure.

(b) While taking the measurement, the eyes should be correctly positioned.

(c) If the edge of the ruler is worn out or broken, the measurement  should be taken from any other full mark of the ruler.

Q. How can we measure a curved line?

Ans. Measuring the length of a curved line: We cannot measure the length of a curved line directly by using a metre scale. We can use a thread or divider to measure the length of a curved line.

Q. How can you measure the height of your classmates?

Ans. To Measure the height of our classmate by using a metre scale. For this, 

* ask the classmate to stand with his back against a wall.

* Make a mark on the wall exactly above his head. 

* Now, measure the distance from the floor to this mark on the wall with a metre scale.

* This measurement is the actual height of of the classmate.

Q. What do you mean by Rest?

Ans. Rest: All the stationary objects which are not in motion and do not change their place with time are said to be at rest.

Q. What do you mean by motion? What are its main types?

Ans. Motion: Motion is a state of objects in which they are moving that is, they are changing their place with the time.

Some of the main types of motion are:

* Rectilinear motion

* Circular motion

* Periodic motion

Q. What do you mean by Rectilinear   motion? Explain with examples.

And. Rectilinear motion: When the objects change their position with time along a straight line is called rectilinear motion.

The motion of vehicle on a straight road, march-past of soldiers in a parade or the falling of a stone are the example of rectilinear motion.

Q. What do you mean by   Circularmotion motion? Explain with examples.

Ans. Circularmotion: Motion of the objects along a circular path is called circular motion. In a circular motion, the object remains at the same distance from a fixed point.

The electric fan or the clock, wheel moves with a circular motion. The Motion of stone tied in a thread and whirled.

Q. What do you mean by Periodic  motion? Explain with examples.

Ans. Periodic motion: The motion which repeats itself after a regular time intervals is called periodic motion.

Motion of a pendulum, a branch of a tree moving to and fro, motion of a swing, strings of a guitar or the surface of drums (tabla) being played, are all examples of periodic motion

Q. What do you mean by the rotational motion?

Ans. Rotational Motion: Motion in which a whole body moves about on an axis is called a rotational motion. Example: motion of a top.

Q. Give an example where two motions are combined together?

Ans. Combination of two or more types of motions: In some situations, the motion of an object may be a combination of two or more of the above mentioned types of motion.

Examples: * Motion of a ball rolling on the ground. Here, the ball is rotating about on its axis but the axis itself is moving along a straight line. Thus, the ball is showing a rectilinear motion as well as rotational motion.

* Motion of earth earth shows rotations on its axis and also shows revolution around the sun.

• 

Q. What do you mean by distance?

Ans. Distance: Measurement of gap between two points in certain units is called distance.

 

Q. How the transport developed? Draw a path of development of transport?

Ans. In ancient times people use animals cards and boards to carry loads.

After the inventionof steam engine led to the developmentof new means of transport. Railroads were made for steam engine driven carriages and wagons. 

Later came automobiles such as motor cars, trucksand buses. Motorised boats and ships wereused as means of transport on water. 

Electrictrains, monorail, supersonic aeroplanesand spacecraft are some of thecontributions of the 20th century.

The SI unit of length is a metre.

1m = 10dm = 100cm = 1000mm

1dm = 10cm = 100mm

1cm = 10mm

Exercise

Chapter 10 - Motion and Measurement of Distances

Q. 1. Give two examples each of modes of transport used on land, water, and air.

Ans. Examples of modes of transport used on 

Land: Bus, car, train, truck

Water:  Ship, boat, Steamer

Air: Aeroplane, helicopter

Q. 2. Fill in the blanks:

(i) One metre is __________ cm.

(ii) Five kilometres is __________ m.

(iii) Motion of a child on a swing is ___________.

(iv) Motion of the needle of a sewing machine is ___________.

(v) Motion of wheel of a bicycle is___________.

Answer.

(i) One metre is 100 cm.

(ii) Five kilometres is 5000 m.

(Explanation:

We know that 1 km = 1000 m

                         5 km = 1000 × 5 

                                   = 5000 m

(iii) Motion of a child on a swing is periodic.

(iv) Motion of the needle of a sewing machine is periodic.

(v) Motion of the wheel of a bicycle is circular motion.

Q. 3. Why can a pace or a footstep not be used as a standard unit of length?

Ans. Because the size of pace or footstep of different people are different so the lengths measured by two different persons using their footsteps will not be the same. Due to this reason pace or a footstep cannot be used as a standard unit of length

Q. 4. Arrange the following lengths in their increasing magnitude:

1 metre, 1 centimetre, 1 kilometre, 1 millimetre

Ans.

1 m = 100 cm

1 cm = 10 mm

1 m = 100 × 10 = 1000mm   

Now,  1 km = 1000 m

1 km = (1000 × 100)cm = 100000 cm = (100000 × 10)mm = 1000000mm

So, arranging 1 metre, 1 centimetre, 1 kilometre, 1 millimetre in increasing order we have:

1mm < 10mm < 1000mm < 1000000mm

Or 1 millimetre < 1 centimetre < 1 metre < 1 kilometre

Q. 5. The height of a person is 1.65 m. Express this in cm and mm.

Ans. Height of the person = 1.65 m

We know that 1 m = 100 cm

1.65 m = 100 × 1.65 = 165 cm

Again, 1 m = 100 cm = 1000 mm

1.65 m = 1.65 × 1000 = 1650 mm

Thus height of person in cm = 165 cm

And height of person in mm = 1650 mm

Q. 6. The distance between Radha’s home and her school is 3250 m. Express this distance in km.

Ans. The distance between Radha’s home and her school is 3250 m.

We know that 1 km = 1000 m

Or  1000 m = 1 km

Or 1m = 1/1000 Km

Thus, 3250 m = (1/1000) X 3250 = 3.25 Km

Therefore, distance between Radha’s home and her school in km = 3.25 km

Q. 7. While measuring the length of a knitting needle, the reading of the scale at one end is 3 cm and at the other end is 33.1 cm. What is the length of the needle?

Ans. Length of the knitting needle is the difference between two readings.

Thus, length of knitting needle = 33.1− 3.0 = 30.1 cm

Q. 8. Write the similarities and the differences between the motion of a bicycle and a ceiling fan that has been switched on.

Ans. Similarity between the motion of a bicycle and a ceiling fan is that both the wheels of bicycle and the fan are moving around a fixed point and possess circular motion.

Differences between the motion of a bicycle and a ceiling fan is that a bicycle has linear motion as it moves forward, whereas ceiling fan does not possess the linear motion.

Q. 9. Why can you not use an elastic measuring tape to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with an elastic tape?

Ans. Elastic tapes are stretchable. So, the length of an elastic measuring tape will change each time due to stretching. So, it will not give correct measurement of a distance. Therefore, we cannot use an elastic measuring tape to measure distance. While measuring the distance with an elastic tape, we will get different values of the same distance each time.

Q. 10. Give two examples of periodic motion.

Ans. Examples of periodic motion are: (any two)

Motion of a pendulum, Motion of a swing, Motion of Earth around the Sun, Motion of a rocking chair etc.