**Lesson.1 Measurements**

**Lesson.1 Measurements**

### I. Choose the correct answer:

1. The girth of a tree can be measured by

- metre scale
- metre rod
- plastic ruler
- measuring tape

Ans : **measuring tape**

2. The conversion of 7m into cm gives ………….

- 70cm
- 7cm
- 700cm
- 7000cm

Ans : **700 cm**

3. Quantity that can be measured is called ………….

- Physical quantity
- Measurement
- Unit
- Motion

Ans : **Measurement**

4. Choose the correct one

- km > mm > cm > m
- km > mm > m > cm
- km > m > cm > mm
- km > cm > m > mm

Ans : **km > m > cm > mm**

5. While measuring length of an object using a ruler, the position of your eye should be

- Left side of the point
- Vertically above the point where the measurement is to be taken.
- Right side of the point
- Any where according to one’s convenience.

Ans : **Vertically above the point where the measurement is to be taken.**

### II. True or False.

1. We can say that mass of an object is 126kg.

Ans : **True**

2. Length of one’s chest can be measured by using metre scale.

Ans : False

3. Ten millimetres makes one centimetre.

Ans : **True**

4. A hand span is a reliable measure of length.

Ans : **False**

5. The SI system of units is accepted everywhere in the world.

Ans : **True**

### III. Fill up the blanks.

1. SI unit of length is symbolically represented as ………..

Ans : **metre**

2. 500 gm = …………….. kilogram

Ans : **½**

3. Distance between Delhi and Chennai can be measured in ………….

Ans : **kilometre**

4. 1m = …………….. cm

Ans : **100**

5. 5km = …………….. m

Ans : **5000**

### IV. Analogy.

1. Sugar : Beam balance ; Lime juice ?

Ans : **Measuring Jar**

2. Height of a person : cm ; length of your sharpened pencil lead ?

Ans : **mm**

3. Milk : volume ; vegetables ?

Ans : **Mass**

### V. Match the following

1. Length of the fore arm | Metre |

2. SI unit of length | Second |

3. Nano | 10^{3} |

4. SI Unit of time | 10^{–9} |

5. Kilo | Cubit |

Ans : 1 – E, 2 – A, 3 – D, 4 – B, 5 – C |

### VI. Arrange the following in the increasing order of unit.

1 Metre, 1 centimetre, 1 kilometre, and 1 millimetre.

Ans : **1 millimetre < 1 centimetre < 1 Metre < 1 kilometre**

### VII. Find the answer for the following questions within the grid

1. 10^{-3} is one __________

Ans : **millimetre**

2. SI Unit of time __________

Ans : **second**

3. Cross view of reading for a measurement leads to ________

Ans : **Error**

4. __________is the one what a clock reads .

Ans : **Time**

5. __________is the amount of substance present in an object

Ans : **Mass**

6. __________ can be taken to get the final reading of the recordings of different of students for a single measurement.

Ans : **Average**

7. __________is a fundamental quantity.

Ans : **Length**

8. __________shows the distance covered by an automobile

Ans : Odometer

9. A tailor use ________to take measurements to stitch a cloth

Ans: **Tape**

10. Liquids are measured with this physical quantity

Ans : **Litre**

### VIII. Answer in a word or two.

1. What is the full form of SI system?

International system of Units.

2. Name any one instrument used for measuring mass.

Beam Balance

3. Find the odd one out

Kilogram | Millimetre | Centimetre | Nanometre |

Ans : **Kilogram**

4. What is the SI Unit of mass?

Kilogram

5. What are the two parts present in a measurement

- Number
- Unit

### IX. Answer in a sentence or two.

1. Define measurement.

The comparsion of an unknown quantity with some known quantity is known as measurement.

2. Define mass.

Mass is the measure of the amount of matter in an object.

3. The distance between two places is 43.65 km. Convert it into metre and cm.

The distance between two places is 43.65 km.

a) Converting into metre :

1 kilometre | = 1000 metre |

43.65 kilometre | = 43.65 x 1000 |

= 43,650 metre |

b) Converting into centimetre:

1 metre | = 100 centimetre |

43650 metre | = 43650 x 100 |

= 43,65,000 centimetre |

4. What are the rules to be followed to make accurate measurement with scale?

- An object should be placed parallel to the scale.
- To avoid parallax error our eye must be vertically above the point, where the measurement has to be taken.
- The head of the measuring object has to coincide with ‘o’ of the scale.
- The measurement has to measure from ‘o’.
- Count the number of centimetre and from there count the number of finer divisions. The count of the division is ‘mm’.

### X. Solve the following

1. The distance between your school and your house is 2250 m. Express this distance in kilometre.

#### Solution :

The distance between school and house | = 2250 m |

1000 metre | = 1 kilometre |

= 2250/1000 | |

= 225/100 = 2.25 | |

2250 metre | = 2.25 kilometre |

2. While measuring the length of a sharpened pencil, reading of the scale at one end is 2.0 cm and at the other end is 12.1 cm. What is the length of the pencil?

#### Solution :

Reading of the scale at one end of pencil | = 2.0 cm |

Reading of the scale at the other end of pencil | = 12.1 cm |

length of the pencil | = 12.1 – 2.0 = 10.1 |

Length of the pencil | = 10.1 cm |

### XI. Write in detail

1. Explain two methods those you can use to measure the length of a curved line.

Two Methods of measuring Length of a curved line :

### i) First Method :

Find the length of a curved line using a string :

Materials needed : A meter scale, a measuring tape, a string and a sketch pen.

#### Method:

- Draw a curved line AB on a piece of paper
- Place a string along the curved line. Make sure that the string covers every bit of the curved line.
- Mark the points where the curved line begins and ends on the string.
- Now, stretch the string along the length of a meter scale and measure the distance between the two markings of the string. Note it.
- This will give you the length of a curved line.

### ii) Second Method :

Measuring the length of a curved line using a divider :

- Draw a curved line AB on a piece of paper
- Separate the legs of the divider by 0.5 cm or 1 cm using a ruler.
- Place it on the curved line starting from one end.
- Mark the position of the other end.
- Move it along the line again and again cutting the line into number of segments of equal lengths.
- The remaining parts of the line can be measured using a scale.
- Count the number of segments
- Therefore, the length of the line = (number of segments × length of each segment) + length of the left over part.