Question

Que. 7) If the fan stops rotating after 21 revolutions, then the angular displacement of blades of fan, while stopping is-----
​

Answer 1

Answer:

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Explanation:

1st case:

We can write the equation of motion for circular motion as:

ω  

2

=ω  

0

2

​

+2aθ  

n

​

 

Now, ω=  

2

ω  

0

​

 

​

,θ=36×2π (given)

So,  

4

ω  

0

2

​

 

​

=ω  

o

2

​

+2α×36×2π

So, α=  

4×144π

−3ω  

0

2

​

 

​

 

2nd case:

0=  

4

ω  

0

2

​

 

​

−2×  

4×144π

3ω  

0

2

​

 

​

×θ

So, θ=24π

So, number of rotations made by the fan before coming to rest =  

2π

24π

​

=12

Answer 2

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