SCIENCE CHAP-10 MOTION & MEASUREMENT TEXTBOOK QUES-ANS

 

CHAPTER 10

MOTION & MEASUREMENT

 

Answers to the questions given in the Check your progress (Pg 137):

Name the following:

1. The distance from the tip of the thumb to the tip of the little finger in a stretched hand.

Handspan

2. The Greek word from which measurement is derived. Metron

3. A quantity that can be measured and expressed in numbers. Physical quantity

4. Another name for arm’s length. Cubit

 

Answers to the questions given in the Check your progress (Pg 138):

 

1. What is the SI unit of temperature? Kelvin

2. How many years make one century? 100 years

3. How much kilograms make one quintal? 100 kg

4. What is the SI unit of time? Seconds

 

Answers to the questions given in the Check your progress (Pg 141):

1. Why is a cubit or a footstep not considered as a standard unit?

The cubit or footstep can vary from person to person.

2. Arrange the following units of length in decreasing order – millimetre, kilometre, metre,

centimetre.

Kilometre, metre, centimetre, millimetre

3. What is length?

Length is the distance between any two points

4. Which two instruments can be used for measuring length?

Ruler, meter scale and measuring tape

Answers to the questions given in the Check your progress:

 

Answers to the questions given in the Let’s exercise

1. Choose the correct option:

a. When the motion of an object is repeated at regular intervals of time, the object is in

Ans: Periodic motion

b. The _____________________ is a standard unit of measurement

Ans: metric system

c. The unit used to measure the length of a cloth is:

Ans: metre

d. A thermometer is used to measure ______________________ of the body.

Ans: temperature

e. Which of the following is an instrument used to measure length?

Ans: measuring tape

2. Fill in the blanks.

a. One kilometre = _________metres. 100.

b. The motion of an object along a straight line is called rectilinear motion.

c. Rest and motion are relative terms.

d. Measuring tape is an instrument used to measure length.

3. State whether the following statements are True (T) or False (F).

a. Cubit is a standard unit for the measurement of length. False

b. The length of a curved line cannot be measured directly with a metre scale. True

c. Ten millimetres is equal to 1 metre. False

d. The motion of a potter’s wheel is an example of a translatory motion. False

a-    ii, b- iii, c- i

5. Answer the following questions in one word or one sentence.

a. What is motion?

An object which changes its position with respect to its surroundings is said to be in

motion.

b. Give one example of curvilinear motion?

A car moving on a curved road, the motion of basketball into the basket, motion of a

roller coaster etc.

c. Convert 5 centimetre to millimetre.

1 centimetre= 10 millimetres,

5 centimetre = 5×10= 50 millimetres

d. Which unit is used to measure larger distances?

Kilometre

6. Answer the following questions in short.

a. What is periodic motion?

A motion that repeats itself at regular intervals of time is called as periodic motion.

b. Explain with the help of an example when an object is said to be at rest?

An object which does not show any change in its position with respect to its

surroundings is said to be in rest. Example the trees or buildings are at rest.

c. What do you mean by measurement?

Measurement means a limited proportion.

7. Give reasons.

a. The motion of the hands of a clock is an example of circular motion.

When a body moves in a circular manner so that its distance from a fixed point

remains same, then the motion is called circular motion. In a clock, the hands move in

circular manner from a fixed point hence it is an example of circular motion.

b. We need standard units of measurement.

The ancient methods of measurement using the body parts were not constant as the

size of body parts varies from person to person. Hence we need standard units of

measurements.

c. Rest and motion are relative terms.

Something that appears to be in motion in relation to one observer may appear to be

at rest in relation to another observer. Hence rest and motion are relative terms.

8. Answer the following questions in detail.

a. Which three precautions should be taken while measuring length?

• Place the ruler along the length that has to be measured.

• If the zero mark on the ruler is worn out or not clearly seen then start measuring the

length from the first full mark that is clearly seen on the ruler. Subtract the first

reading from the second. The difference will give you the actual length.

• Read the metre scale from the front and not the sides. Position your eye just above

the point where you want to measure the length or note the reading.

b. Give an example of a body showing two different types of motions at the same time.

Name and explain both the motions.

i. The movement of a drill machine- shows both circular motion and translatory

motion.

ii. The motion of a car on a road- shows both rectilinear as well as curvilinear.

iii. The motion of the wheels of a car- shows both rectilinear and circular motion.

c. Name and explain any three ancient methods of measurement.

Foot - The length from the heel to the big toe of a person.

Handspan – The distance from the tip of the thumb to the tip of the little finger in a

stretched hand.

Cubit or Arm’s length – The length of the forearm from the tip of the middle finger

to the elbow.

9. Practical based question.

a. Mona was worried as the ruler in her geometry box had broken edges. Suggest how

she can use this ruler for measuring the length of a line.

If the zero mark on the ruler is worn out or not clearly seen then start measuring the

length from the first full mark that is clearly seen on the ruler. Now, subtract the first

reading from the second. The difference will give the actual length of the line.

 

10. Diagram based questions

Look at the following pictures and identify the types of motion shown in each of them.

 

11. HOTS (Higher Order Thinking Skills)

a. Urvashi needs 5 m of a particular cloth to get her outfit stitched. She could buy 4 m of the

cloth. Will she be able to get her outfit stitched?

NO.

b. How will you measure the thickness of a one rupee coin using a ruler?

(Hint: Take about 10-15 coins and stack them together to take the total thickness)

Take 10 coins and make a stack of it. Calculate the length of the stack and note down

the reading. After you get the measurement, divide the number by 10 and you will get

the thickness of one rupee. (Note take 10 coins of similar kind of one rupee)

 

12. Value based questions

Read the paragraph and answer the questions given below.

Raju’s mother gave him and his older sister a list of items to be purchased from the grocery.

Raju handed over the list to the grocer. The grocer started packing the items. Raju’s sister

noticed that the grocer was not using the weighing scale. She asked the grocer to use the

weighing scale and then give the items.

i. Which physical quantity is measured by a weighing scale? Mass

ii. Why do you think the shopkeeper did not use the weighing scale? He didn’t want to give the exact quantities

iii. What values were shown by Raju’s sister? Observant and Straightforward