A smooth circular groove has a smooth vertical wall as shown in figure. A block of mass $m$ moves against the wall with a speed $v$. Which of the following curve represents the correct relation between the normal reaction on the block by the wall $( N )$ and speed of the block $(v)$ ?

An aircraft executes a horizontal loop at a speed of $720\; km/h$ with its wings banked at $15^o$. What is the radius of the loop in $km$?

Concretemixture is made by mixing cement, stone and sand in a rotating cylindrical drum . If the drum rotates too fast, the ingredients remain stuck to the wall of the drum and proper mixing of ingredients does not take place. The maximum rotational speed of the drum in revolutions per minute (rpm) to ensure proper mixing is close to (Take the radius of the drum to be $1.25\, m$ and its axle to be horizontal)

A gramophone record is revolving with an angular velocity $\omega$. A coin is placed at a distance $r$ from the centre of the record. The static coefficient of friction is $\mu  .$ The coin will revolve with the record if

A coin placed on a rotating table just slips if it is placed at a distance $4r$ from the centre. On doubling the angular velocity of the table, the coin will just slip when at a distance from the centre equal to

Radius of the curved road on national highway is $R$. Width of the road is $b$. The outer edge of the road is raised by $h$ with respect to inner edge so that a car with velocity $v$ can pass safe over it. The value of $h$ is