SEBA Class 7 Science Part II Chapter 1 Answer 2026 | Measurement of Time and Motion | Class 7 Science Part II Chapter 1 Books Solution

CHAPTER 7

Measurement of Time and Motion

EXERCISE

Q. 1. Darken the circle of correct answer

(i) Speed of a car that covers 300 m distance in 30 s is

(a) 10 m/s
(b) 20 m/s
(c) 30 m/s
(d) 40 m/s

Ans. (a)

(ii) Speed 72 km/h can be expressed as –

(a) 40 m/s
(b) 60 m/s
(c) 10 m/s
(d) 20 m/s

Ans. (d)

(iii) SI unit of average speed is

(a) km/s
(b) m/h
(c) m/s
(d) mm/s

Ans. (c)

(iv) Smallest time interval that can be measured in a normal wall clock is

(a) 1 Hour
(b) 1 Minute
(c) Half an hour
(d) 1 Second

Ans. (d)

Q. 2. Fill up the blanks

(a) An object moving along a straight line with a constant speed is said to be in _________ motion.

Ans. (a) Uniform linear

(b) If the speed of an object moving along a straight line keeps changing, it is said to be in __________ motion.

Ans. Non-uniform linear

Q. 3.

A bus travels at a speed of 20 m/s and covers a distance of 288 km. How much time does it take? Find the answer in hour, minute and second.

Ans.

20 m/s = 72 km/h

Distance = 288 km.

Time taken = 288/72 = 4 h

In minute:

Time taken = 4 × 60 min = 240 min

In second:

Time taken = 240 × 60 s = 14,400 s

Q. 4.

Write three examples of non-uniform motion from your daily life.

Ans.

(i) Movement of a bus on a crowded street.

(ii) Motion of a runner during a competition.

(iii) Movement of a ball thrown straight upward.

Q. 5.

Why is uniform motion over a long distance considered an ideal case? Explain with examples.

Ans. Uniform motion over a long distance is called an ideal case because in practical life it is very difficult for an object to move continuously with the same speed for a long time. Most objects change their speed while moving.

For example, a person cannot walk or run at the same speed all the time. In the same way, a vehicle on the road also cannot maintain a fixed speed due to traffic and road conditions.

Q. 6.

Make list of 5 animals or objects and compare their speed with average walking and running speed of human.

Ans. Do it yourself.

Q. 7.

Assertion: A car moving through crowded city streets often has non-uniform motion.

Reason: In non-uniform motion, an object travels unequal distances in equal intervals of time.

Choose the correct option:

(a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

(b) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

(c) Assertion is true, but Reason is false.

(d) Assertion is false, but Reason is true.

Ans. (a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Q. 8.

Choose any track and field event, such as the 100 m, 200 m, or 400 m race. Using the Internet, find the current national record and the Olympic record for the same event. Compare the timings.

Event	National record	Olympic record	Difference
100m	10.18 sec.	9.63 sec.	0.55 sec.
200m	20.32 sec.	19.30 sec.	1.02 sec.
400m	45.12 sec.	43.03 sec.	2.09 sec.

Q. 9.

A train travels 120 km in the first two hours, 150 km in the next two hours, and 100 km in the last hour. Is the motion uniform? Justify your answer. Also, calculate the train’s average speed.

Ans. The motion is not uniform. Because the train travels unequal distances in equal intervals of time.

Q. 10.

Partha decides to visit his friend in a nearby town 60 km away. He starts his journey on his scooter at 8:00 a.m. and rides at a speed of 40 km/h for the first 30 km. Due to traffic, he slows down and covers the next 20 km at 30 km/h. For the last 10 km, the road is clear, and he increases his speed to 60 km/h.

(i) At what time did Partha complete the entire journey?

(ii) What is the total distance travelled by Partha?

(iii) Calculate the average speed of Partha for the whole journey.

(iv) Was Partha’s motion uniform or non-uniform? Justify your answer.

(v) If Partha has travelled the entire 60 km at a constant speed of 40 km/h, how much time would he have saved or lost compared to the actual time taken?

Ans.

For the first 30 km:

For the next 20 km:

For the last 10 km:

= 1h + 35 min = 1h 35 min

(i) Partha completed the entire journey after 1 h 35 min. at 9:35 a.m.

(ii) Total distance travelled by Partha = 60 km

(iii) Average speed = 37.89 km/h

(iv) Partha’s motion was non-uniform. Because he kept changing his speed during the journey.

(v) For a constant speed of 40 km/h

Amount of time he would have saved compared to the actual time taken.

Q. 11.

Complete the concept map.

Q. 12.

A spacecraft moving at a constant speed of 36,000 km/h in space, then complete the table.

Time (s)	0	2	4	6	8	10
Distance (m)	0	20000	40000	60000	80000	100000

Q. 13.

The table given below shows the time and distance travelled by a car. Using the data provided, identify the type of motion exhibited by the car, Also, determine during which part of the journey was the car moving at the fastest speed and during which part was moving at the slowest speed. Finally, calculate the average speed of the car for the entire journey.

Time (s)	0	10	20	30	40	50
Distance (m)	0	500	800	1500	1700	3000

Ans. The type of motion exhibited by the car is non-uniform.

The part of the journey during which the car was moving at the fastest speed was between 40s and 50s.

The part of the journey during which the car was moving at the slowest speed was between 30 s and 40 s.

OLD Question Answer
From fibers to cloth 

Exercise:

1) You feel familiar with the pre-primary verses below .

i) Baa-Baa black sheep, have you any wool.

ii) Mary had a little lamb, whose fleece was white as snow.

Answers to the questions below .

A)  Which part of Black sheep  has wool ?

Answer:  Black sheep  has wool .

b) What is the name of the sheep ?

Ans:  The wool of the sheep’s wool is burnt in Nombore.

(2) Patpalu means it is (a) caterpillar (b) larva  .  Which of the following is clean ?

i)  a.

ii)  b.

iii)  Both a and b.

iv)  A and B are neither .

Answer:  iii)  Both A and B.

3) Put some fire on the floor .

i)  Yak.

ii)  Camel.

iii)  Goat.

iv) Normal dogs .

Answer:  Normal dogs.

4) Do you understand the words below ?

i)  rearing.

ii)  Shweering or nom khuroa.

iii)  Recham or jute industry.

Ans:  i)  Rearing – Animals are taken care of in terms of feeding ,  grazing ,  breeding and also meat and  .

    ii)  Shweering or Nom Khuroa  – Nombo antara is obtained through the thin bark of the sheep’s body .  This method is called mundan or animal name khuroa buli koa.

    iii) )  Silk or jute industry –  Jute spinning and jute cultivation or Pohak Recham or jute industry .

5) Below are the layers of the prepared system .  Write the rest of the notes .

Owning or naming , ________,  charting or sharing , ___________, ___________, _____________

Ans:  Simmering or name drilling,  Abrasion or cleaning ,  Charting or splitting ,  Dyeing ,  Fanioa

7) Give below any two words related to jute production .

Textile industry ,  horticulture ,  horticulture ,  beekeeping ,  arboriculture .

Answer:  Recham Shilpaand  Nunigarh Kheti ,  these two words are involved in jute production .

8)  Match ‘ A ‘  part to  ‘ B ‘  part

‘ A ‘  part            ‘ B ‘  part                   

1) Scouring             a) Produces jute yarn .

2) Salt tree leaves                  b) Wool producing animals .

3) Yak                                 c) Jute food .

4) Lataguti                          d) Mahura Fura.

                                           (e) Purification of Kati Loa Noma with bark juice.

Answer:

    1) Scouring or Abrasion- (e) Cleaning of cut iron with bark

    2) Nuni tree leaves –      c) jute palm food .

    3) Yak  –  b) Wool producing animal                     .

    4) Letaguti-  a) Produces jute yarn               .

( 9) Based on the text, it is arranged in a sequence of words. Fill in the blanks with the help of English because of the words.

Tallai 2) Now thatyakarwool can be planted in sufficient quantity and is generally used.- Ladakht. 3) First country to start Recham or Jute industry.- China. 5) Jute and name it-  Recham. Pathalikai 1) Pat Palu life cycle is the back stage of Kani. –  Who are the children? 4) The material released during the horizontal transformation of the column.-  Protein. 6) The life cycle of jute pulp is the layer behind the letter.-  Chakri. 7) Sheep, a part of the bark of a primitive animal thatcanbe burned. –  Nom.