The half-life period of a radioactive element $$x$$ is same as the mean life time of another radioactive element $$y$$. Initially, both of them have the same number of atoms. Then,
One end of a spring of force constant $$k$$ is fixed to a vertical wall and other to a body of mass $$m$$ resting on a smooth horizontal surface. There is another wall at a distance $$x_0$$ from the body. The spring is then compressed by $$2 x_0$$ and released. The time taken to stike the wall is
A particle of mass $$m$$ is moving in a horizontal circle of radius $$r$$ under a centripetal force given by $$\left(-k / r^2\right)$$, where $$k$$ is a constant. Then
A plane glass mirror of thickness $$3 \mathrm{~cm}$$ of material of $$\mu=\frac{3}{2}$$ is silvered on the back surface. When a point object is placed $$9 \mathrm{~cm}$$ from the front surface of the mirror, then the position of the brightest image from the front surface is