A coin is placed on a disc. The coefficient of friction between the coin and the disc is $\mu$. If the distance of the coin from the center of the disc is $r$, the maximum angular velocity which can be given to the disc, so that the coin does not slip away, is:

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

The maximum velocity (in $ms^{-1}$) with which a car driver must traverse a flat curve of radius $150 \,m$ and coefficient of friction $0.6$ to avoid skidding is

A car when passes through a convex bridge exerts a force on it which is equal to

A body of mass $1\, kg$ tied to one end of string is revolved in a horizontal circle of radius $0.1\, m$ with a speed of $3$ revolution/sec, assuming the effect of gravity is negligible, then linear velocity, acceleration and tension in the string will be

A vehicle of mass $200\,kg$ is moving along a levelled curved road of radius $70\,m$ with angular velocity of $0.2\,rad / s$. The centripetal force acting on the vehicle is $.........\,N$