Motion - NCERT Exercises | Class 9 Physics

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✅ In this video,

✔️ Class: 9
✔️ Subject: Physics
✔️ Chapter: Motion
✔️ Topic Name: NCERT Exercises
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00:00 Physics Introduction: Motion
00:18 NCERT Exercises Question 1
05:48 Question 2
10:26 Question 3
12:02 Question 4
12:34 Numericals Questions 1
14:59 Question 2
17:13 Website Overview
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Points covered in this video:-

Question 1. An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?
Solution: Here, Total time = 2 minutes 20 seconds
= 2 x 60 seconds + 20 seconds
= 120 seconds + 20 seconds
= 140 s
Now, in 40 s, the number of rounds completed = 1
So, in 140 s, the number of rounds completed = 1 x 140 = 3.5

(a) Calculation of distance covered in 3.5 rounds
The diameter of circular track is given to be 200 m, so the radius (r) of the circular track will be half of it, which is 200/2 = 100 m
Now, Distance covered in 1 round = Circumference of circular track
= 2πr
= 2 x (22/7) x 100 m (Because π = 22/7)
= 328.57 m
And, Distance covered = 628.57 x 3.5 m
In 3.5 rounds = 2200 m

(b) Calculation of displacement in 3.5 rounds
The athlete makes three and a half rounds (3.5 rounds) of the circular track. Now, if the athlete start from point A (see figure), then after three complete rounds, he will reach at the same point A. and when the athlete again starts from point A and makes the remaining half round, he will reach point B (which is diametrically opposite to A). so, the displacement of athlete will be equal to diameter of the circular track which is 200 m. .

[jaideepsingh-ixlk]

How many students are watching this before one day of exam😂😂

[ghostxff]

Question 3 is wrong
Because 32×4=128
And you solve 32×4=96

[nightshade-nemesis]

3:11 Mam, distance covered in 1 round= 328.57 m. but distance covered in 3.5 rounds = 628.57 * 3.5. Here you have multiplied 628.57 by 3.5. But the distance covered in 1 round is 328.57m

[SatishKumar-vymr]

3:26 Circumference of circular track
=2pie×r
=2×22/7×100
=328.57m
Distance covered=628.57×3.5

And how (628.57) is come when upper caculation is 328.57🧐
EXPLAIN IT!

[ajayagarwal]

Ma'am hum ko pata kese chalega ki konsa equation kis main put karna hai????

[pankajtomar]

Where are other questions?😡 NCERT numericals ko bhi aadhe pe choar (leave)diya aise hum kaise karrnge😡

[kaushalpeshavariya]

3:33
Mam, you find distance 328.57
And then when you multiply you write 628.57 why?

[anishpal]

Mam vo 628.57🙄 nahi hoga 328.57😄 hoga 👍👍👍

[santoshgupta]

Mam whoile taking the average velocity from AtoC why we are considering 210s, why not subtracting time

[shahidraza]

Mam when I multiple 268.57 to 3.5, I get 2199.995
And u say it is 2200
How can be it possible??
Tell me 😡😡😡

[Nirbhay-Singh]

I am having one problem 🙁 . May I ask?

[Ayanshs]

3:10
Ma'am when we multiply 2 X 22/7 X 100 we get 628.57 and not 328.57..and that's why you have multiplied 628.57 X 3.5 in the next line..
.so that is wrong written there..!! Plz look at these silly mistakes...!!

[ujjawalgamer]

Ma'am there is a mistake in distance. There is 628.57 not 328.57 at 3:11☺☺☺☺

[allinonesiddham]

What!!____11:37
32 is multiplied by 4 = 96🤯🤯
Reality. ____ you did that wrong 8x4x3 = 96

[pujabasfore]

Mam na galti ki hai question 3 ka s=ut+1/2at²
S = 0+1/2 ×3×8²
Her mistake is 32×4=96??? How it will be like this
S = 0 + 1/2× 3×8²
S= 3/2×8×8
S= 32×3 = 96 it's okay miss

[yadavanamika]

Ma'am distance 328.57 hai to aapne phir se 328.57 × 3.5 krna
Aapne 628.57× 3.5 kuu kiya h????
Ma'am please tell me????

[rx.feverpitch]

Mam in question 2 time tacken was 180 seconds =3 min

[jsingh]

Mam apne 3rd question me 8×4=32 aaya ha apne fir 32×4 kr diya aur answer likh diya 96 jo galat ha... answer is 128 when we multiply 32×4. 😂😂

[withlovesakshi]

Thank You Magnet Brains for providing such a nice teacher... thank You Vibhuti Mam for your nice explanation and detailed information...

[bhashhkar_]

Question 3 is Question 4 in my book
And Question 4 is question 7 in my book