Question

If the kinetic energy of a particle moving with a constant speed on a circular speed on circular path of radius $4m$ is $100J$. Then the centripetal force will be

• A. $25N$
• B. $50N$
• C. $40N$
• D. $60N$

Answer 1

The correct option is A $25N$

During centripetal force $\frac{{mV}^2}{r}=\frac{K}{r^2}$

or, ${mV}^2=\frac{K}{r}$

Kinetic energy $=\frac{1}{2}\times \frac{K}{r}$ (putting the value of ${mV}^2$)

$K.F=\frac{K}{2r}⟶\left(1\right)$

Potential energy $=fdr$

$PF=\frac{K}{r^2}dr$

$\frac{1}{2}{mV}^2=100(K.E)$

or, ${mV}^2=200$

or, $V^2=\frac{200}{m}⟶\left(1\right)$

Putting equation $\left(1\right)$ in the equation $\left(2\right)$

Now, $\frac{{mV}^2}{r}=\frac{200}{4}⟶\left(2\right)$

$=25$ J