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 #1
avatar+11912 
0
Oct 3, 2014
 #1
avatar+33661 
+5

The angle the strings make with the horizontal must be 30°, so the radius of rotation must be

r = 1.59*cos(30°) metres

 

Resolve forces in vertical and horizontal directions.  These must each be balanced.

 

Vertical:  T1sin(30°) = T2sin(30°) + mg  ...(1)  

where T1 is tension in upper string (58.2N); T2 that in lower string; m is mass of ball (1.14kg) and g is gravitational acceleration (9.8m/s2)

 

Horizontal:  T1cos(30°)+T2cos(30°) = mv2/r ...(2) 

where v is speed of ball.

 

From (1)  T2 = T1 - mg/sin(30°)   ...(3)

                   =  58.2 - 1.14*9.8/sin(30°)

 

$${\mathtt{T2}} = {\mathtt{58.2}}{\mathtt{\,-\,}}{\frac{{\mathtt{1.14}}{\mathtt{\,\times\,}}{\mathtt{9.8}}}{\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{sin}}{\left({\mathtt{30}}^\circ\right)}}} \Rightarrow {\mathtt{T2}} = {\mathtt{35.856}}$$

T2 ≈ 35.9 Newtons

 

Use (3) in (2)

T1cos(30°) + T1cos(30°) - mgcos(30°)/sin(30°) = mv2/r 

v2 = (r/m)*(2T1cos(30°) - mgcos(30°)/sin(30°))

    = (1.59*cos(30°)/1.14)*(2*58.2*cos(30°) - 1.14*9.8*cos(30°)/sin(30°))

 

$${\mathtt{v}} = {\sqrt{\left({\frac{{\mathtt{1.59}}{\mathtt{\,\times\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{30}}^\circ\right)}}{{\mathtt{1.14}}}}\right){\mathtt{\,\times\,}}\left({\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{58.2}}{\mathtt{\,\times\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{30}}^\circ\right)}{\mathtt{\,-\,}}{\frac{{\mathtt{1.14}}{\mathtt{\,\times\,}}{\mathtt{9.8}}{\mathtt{\,\times\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{30}}^\circ\right)}}{\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{sin}}{\left({\mathtt{30}}^\circ\right)}}}\right)}} \Rightarrow {\mathtt{v}} = {\mathtt{9.919\: \!048\: \!659\: \!810\: \!567}}$$

v ≈ 9.92 metres/sec

 

.

Oct 3, 2014
 #129
avatar+118723 
0

Sat 4/10/14

1) BREAKING NEWS - THE TOWN CRIER IS ANNOUNCING A VERY IMPORTANT MESSAGE.

http://web2.0calc.com/questions/hear-ye-hear-ye

1) Thanks Rosala, your laughs are always great.   

http://web2.0calc.com/questions/let-s-end-the-day-with-a-laugh_3

2) I like these.  Thanks for the answer CPhill.   

http://web2.0calc.com/questions/how-do-i-make-100-using-four-4s

3) Graphing tangent function.  Thanks to Chris and Melody.

http://web2.0calc.com/questions/which-graph-best-represents-tan-x-2-y-pictures-included

4) What happens if a number is raised to the power of 0?  Thanks for promoting the discussion Rosala.

http://web2.0calc.com/questions/how-do-you-plug-in-10-to-the-0-power-on-a-calculator

  

♫♪  ♪ ♫                                ♬ ♬ MELODY ♬ ♬                           ♫♪  ♪ ♫ 

Oct 3, 2014
 #304
avatar+118723 
+3

@@ End of Day Wrap       TFri 3/10/14        Sydney, Australia      Time 6:55pm      ♬  

 

Good evening everyone,

 

Today our fantastic answerers have been CPhill, Geno3141, alan, AzizHusain, angelicaMarrufo, Bugzy28871, Dragonslayer554, aoanewbie and The Ghost of Web3calc.   Thank you all.     

 

Aziz has visited us today.  That is great, we have all miss you Aziz.  

 

Now for some interest posts:

 

1) The Ghost of Web2.0 calc has graced us with a visit, laying a lay of lavish wonderment at the feet of our dear Princess Kitty.

http://web2.0calc.com/questions/kitty-3-and-cphill-wait

2) Playing with the imaginary number i

http://web2.0calc.com/questions/what-does-i-equals-to

3)Trailing zeros in factorials.  I like these.  Thanks Gino and Chris.   

http://web2.0calc.com/questions/number-2014-how-many-0-s-it-got-in-the-row-at-the-end-of-that-number

4) Graphing Trig  (Gino and Melody)

 http://web2.0calc.com/questions/math-help_38

5) I really like your answer Gino.  

 http://web2.0calc.com/questions/nothing_4

6) More Physics from Alan, I really must find the time to learn from you Alan.   Thank you.

http://web2.0calc.com/questions/jake-drags-a-sled-of-a-mass-of-25kg-across-the-snow-the-sled-is-attached-to-a-rope-that-he-pulls-wut-a-force-of-50n-at-an-angle-of-32degree

7) Something interesting for the children.

 http://web2.0calc.com/questions/what-are-fractals

 

Thanks all, 

 

                   ♫♪  ♪ ♫                                ♬ ♬ MELODY ♬ ♬                           ♫♪  ♪ ♫ 

Oct 3, 2014

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