The force of mutual attraction between any two objects by virtue of their masses is

The error in the measurement of force acting normally on a square plate is $3 \%$. If the error in the measurement of the side of the plate is $1 \%$, then the error in the determination of the pressure acting on the plate is

For a particle moving along a straight line path, the displacements in third and fifth seconds of its motion are 10 m and 18 m respectively. The speed of the particle at time $t=4 \mathrm{~s}$ is

The vertical displacement ( $y$ in metre) of a projectile in term of its horizontal displacement ( $x$ in metre) is given by $y=\left(\sqrt{3} x-0.2 x^2\right)$. The time of flight of the projectile is

(Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )