A stone is moved in a horizontal circle of radius 4m by means of a string at a height of 20m above the ground. The string breaks and the particle flies off horizontally, striking the ground 10m away. The centripetal acceleration during circular motion is

What is an artificial satellite? Name any two types of artificial satellite and state their functions.

A small block of mass $100 \mathrm{g}$ is tied to a spring of spring constant $7.5 \mathrm{N} {\mathrm{m}}^{-1}$ and length $20 \mathrm{cm}.$ The other end of spring is fixed at a particular point $A.$ If the block moves in a circular path on a smooth horizontal surface with constant angular velocity $5 \mathrm{rad} {\mathrm{s}}^{-1}$about point $A,$ then tension in the spring is

Two stones of masses $m$ and $2m$ are whirled in horizontal circles, the heavier one in radius $\frac{r}{2}$ and the lighter one in radius $r$. The tangential speed of lighter stone is $n$ times that of the tangential speed of the heavier stone. They are reported to experience the same centripetal force. The value of $n$ is, 

A $500\mathrm{ }\mathrm{k}\mathrm{g}$ car takes a round turn of radius $50\mathrm{ }\mathrm{m}$ with a velocity of $36\mathrm{ }\mathrm{k}\mathrm{m}/\mathrm{h}\mathrm{r}$ . The centripetal force is-

Name a physical quantity which (i) varies (ii) remains constant when a body moves in a uniform circular motion.

The earth revolves around the sun in an orbit of radius $1.5\times {10}^{11} \mathrm{m}$ once in a year. Calculate the centripetal acceleration of the earth.