As shown in figure, a $70\,kg$ garden roller is pushed with a force of $\overrightarrow{ F }=200\,N$ at an angle of $30^{\circ}$ with horizontal. The normal reaction on the roller is $.......\,N$ $\left(\right.$ Given $\left.g =10\,m s ^{-2}\right)$

There are three forces $\vec {F_1}$, $\vec {F_2}$ and $\vec {F_3}$ acting on a body, all acting on a point $P$ on the body. The body is found to move with uniform speed.

$(a)$ Show that the forces are coplanar.

$(b)$ Show that the torque acting on the body about any point due to these three forces is zero.

The horizontal acceleration that should be given to a smooth inclined plane of angle $sin^{-1}\, (1/l)$ to keep an object stationary on the plane relative to the inclined plane is

A pebble of mass $0.05\; kg$ is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble,

$(a)$ during its upward motion,

$(b)$ during its downward motion,

$(c)$ at the highest point where it is momentarily at rest.

Do your answers change if the pebble was thrown at an angle of $45^o$ with the horizontal direction? Ignore air resistance.

Define impulse of force. Time derivative of momentum gives which physical quantity ?

An iron sphere weighing $10\, N$ rests in a $V$ shaped smooth trough whose sides form an angle of $60^o$ as shown in the figure. Then the reaction forces are