Which force balance the weight of object, when it is tied at one end of string and rotated horizontally exactly in a plane parallel to ground?

Grade:Upto college level

2 Answers

Askiitians Expert Bharath-IITD
23 Points
14 years ago

Dear Sachin,

Generally in the cases of motion of the string in circular motion with one end of tied to an object, the object experiences the forces in equilibrium.

1. Force due to the rotational motion .ie. centripetal force--- Fr=mv2/r,

2. Force due to gravity --- F = mg,

3. Tension in the string T.

Now when we are rotating at low speeds where Fr and F are comparable then the object will rotate making angle θ with the vertical such that the resultant force FT = √[ Fr2 + F2] is balanced by the tension in the string T.

We also have tan θ = Fr /F

So we spin the object such that its contribution to the square sum is more than the force due to gravity then the object becomes horizontal thus there is no necesscity to balance the gravitational force as it is negligible.

So when Fr is very large then θ = 900

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Adapa Bharath

Badiuddin askIITians.ismu Expert
148 Points
14 years ago

Dear Sachin

Resultant of Weight and centrifugal force is balance by tension in spring

when rotation speed is very high then

centrifugal force is very large compair to weight of the mass. angle made by string in this case with the vertical is almost 90 degree(not equal to 90).

string not rotated horizontly but with a very small angle with horizontal.

if sting is not completly horizontal then its tension must have vertical component also which balance the weight of the mas

Regards

Badiuddin

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