Question

A stone of mass 1kg is tied to the end of a string of 1 m length. It is whirled in a vertical circle . If the velocity of the stone at the top be 4m/s. What is the tension in the string (at the instant ) ?

1. 6N
2.12N
3.5N
4.10N

Answer 1

Hi friend,

Since it is instant,



We know that,

Tension= mv²/r-mg

Tension= 1×(16/1)-1×(1×10)

Tension= 6N

The answer is option (a).

Hope this helped you a little!!!

Answer 2

The string tension is 6N.

Solution:

The given question is solved using the formulation by forming an equation for the given motion, which is as follows,

As we know that the given system has mass m = 1 kg

String length taken as radius of the circular motion r = 1 m

Velocity of the stone = 4 m/ s

Thereby, the equation for the motion be formed as given below,

T = Force due to circular motion – Force due to mass

$\bold{\begin{aligned} T &=\frac{m v^{2}}{r}-m g} \\ T &=\frac{1 \times 4 \times 4}{1}-(1 \times 10) \end{aligned}$

T = 16 – 10

T = 6 N