At the instant $t = 0$ a force $F = kt$ ( $k$ is a constant) acts on a small body of mass $m$ resting on a smooth horizontal surface. The time, when body leaves the surface is
$mg\,k\,sin\,\alpha $
$\frac{{k\,\sin \,\alpha }}{{mg}}$
$\frac{{mg\,\sin \,\alpha }}{{k}}$
$\frac{{mg}}{{k\,\sin \,\alpha }}$
An $80\, kg$ person is parachuting and is experiencing a downward acceleration of $2.8\, m/s^2$. The mass of the parachute is $5\, kg$. The upward force on the open parachute is ........... $N$ (Take $g = 9.8\, m/s^2$)
Write condition for equilibrium when two force act on a particle.
A false balance has equal arms. An object weigh $X$ when placed in one pan and $Y$ when placed in other pan, then the weight $W$ of the object is equal to
A $1 \mathrm{~kg}$ mass is suspended from the ceiling by a rope of length $4 \mathrm{~m}$. A horizontal force ' $F$ ' is applied at the mid point of the rope so that the rope makes an angle of $45^{\circ}$ with respect to the vertical axis as shown in figure. The magnitude of $F$ is: