A small stone of mass 100 g in rotated I a verticlal circle of radius 40 cm. What is the minimum speed needed at the lowest point for looping the loop? Also find the tension in the string at this point `(g=10ms^(-2)).`

Options

A. 4.47 and 6 N
B. 4.47 and 12 N
C. 2.47 and 6 N
D. 4.47 and 16 N

Answer

A

Explanation

`v_(min)=sqrt(5gr)`
`T_(i)=(mv_(min)^(2))/(r)+mg=6mg`
`v_(min)=sqrt(5gr)=sqrt(5xx10xx0.4)=4.47 ms^(-1)`
`T=(mv_(min)^(2))/(r)+mg=6mg=6xx0.1xx10=6N`