A block of metal, of 25 g mass moves down without acceleration when the plane is inclined at an angle of $30^{\circ}$. When the inclination is increased by $30^{\circ}$, find the downward acceleration of the block.

A machine gun fires a bullet of mass m with a velocity of $1000 \mathrm{~m} / \mathrm{min}$. The man holding the gun can exert a force of 200 N on the gun. The product of mass of each bullet and the number of bullets fired in one sec is

A body of mass 10 kg is moving up on an inclined plane of $30^{\circ}$ with an acceleration $2 \mathrm{~ms}^{-2}$. Find the force required, if the coefficient of friction between the object and the plane surface is $\frac{\sqrt{3}}{6}$, [given $g=10 \mathrm{~ms}^{-2}$ ].

A body weighing 125 kg just slides down a rough inclined plane that rises 1 m in every 2 m . What is the coefficient of friction?