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Please help.

Guest Apr 2, 2017
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 #1
avatar+77060 
+2

Here's the third one......

 

Circumference of coaster = 2pi (radius)

 

12.56  = 2pi (radius)    divide by 2pi

 

12.56 / [ 2pi] = radius =    6.28/pi  inches

 

Then....the radius of the glass  =  [ 6.28/pi -  1/2] inches

 

So......the circumference of the glass =

 

2 * pi * radius  =

 

2 * pi * [ 6.28/pi - 1/2) ]  ≈ 9.42 in 

 

 

cool cool cool

CPhill  Apr 2, 2017
 #2
avatar+77060 
+2

Here's the frist one :

 

The linear distance traced out by one revolution of the ball will be

 2* pi (1 inch)  = 2pi inches

 

And 5 ft  = 60 inches

 

So......,the number of revolutions  =  60 / [ 2 pi]   =  30 / pi ≈ 9.5 revolutions

 

 

cool cool cool

CPhill  Apr 2, 2017

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