Question 105: Work, Energy and Power & Circular Motion

Question

A boy ties a stone of mass 100 g to the end of a 2 m long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of 80 N. If the maximum speed with which the stone can revolve is $${K \over \pi }$$ rev./min. The value of K is :
(Assume the string is massless and unstretchable)

Accepted Answer

$$T = m{\omega ^2}r$$
$$ \Rightarrow 80 = 0.1 	imes {\left( {2\pi  	imes {K \over \pi } 	imes {1 \over {60}}} ight)^2} 	imes 2$$
$$ \Rightarrow {{800} \over 2} = {{{K^2}} \over {900}}$$
$$ \Rightarrow K = 30 	imes 20 = 600$$

Answer

400

Answer

300

Answer

600

Answer

800

Work, Energy and Power & Circular Motion

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