Question

A block of mass 1 kg is tied to a string length 1m, the other end which is fixed. The block is moved on a smooth horizontal table with constant speed $10m{s}^{-1}$. Find the tension in the string.

Answer 1

The ball in Fig. does not accelerate vertically. Therefore, we model it as a particle in equilibrium in the vertical direction. It experiences a centripetal in acceleration in the horizontal direction. In this case, centripetal force is provided by tension.
$\sum F_y=N-mg=0$
N= mg (i)
$\sum F_x=T=m{a}_c=\frac{m{v}^2}{r}$ (ii)
$T=\frac{m{v}^2}{r}=\frac{1\times {10}^2}{1}=100N$