Two particles of mass $m$ each are tied at the ends of a light string of length $2a$ . The whole system is kept on a frictionless horizontal surface with the string held tight so that each mass is at a distance $'a'$ from the centre $P$ (as shown in the figure). Now, the mid-point of the string is pulled vertically upwards with a small but constant force $F$ . As a result, the particles move towards each other on the surface. The magnitude of acceleration, when the separation between them becomes $2x$ , is
$\frac{F}{{2m}}\,\frac{a}{{\sqrt {{a^2} - {x^2}} }}$
$\frac{F}{{2m}}\,\frac{x}{{\sqrt {{a^2} - {x^2}} }}$
$\frac{F}{{2m}}\,\frac{x}{a}$
$\frac{F}{{2m}}\,\frac{{\sqrt {{a^2} - {x^2}} }}{x}$
A uniform thick string of length $5\,m$ is resting on a horizontal frictionless surface. It is pulled by a horizontal force of $5\,N$ from one end. The tension in the string at $1\,m$ from the force applied is ......... $N$
In the figure shown, a balloon is pressed against a wall. It is in equilibrium and maximum compresed state.$\vec F_1\,=$ force of balloon on hand of man $;$ $\vec F_2\,=$ force of balloon on wall $;$ $\vec F_3\,=$ friction $;$ $\vec F_4=$ weight of balloon. Choose the correct statement.
In the system shown in the adjoining figure, the tension $T_2$ is
Give the magnitude and direction of the net force acting on
$(a)$ a drop of rain falling down with a constant speed,
$(b)$ a cork of mass $10\; g$ floating on water,
$(c)$ a kite skillfully held stationary in the sky,
$(d)$ a car moving with a constant velocity of $30\; km/h$ on a rough road,
$(e)$ a high-speed electron in space far from all material objects, and free of electric and magnetic fields.
There are four forces acting at a point $P$ produced by strings as shown in figure. Which is at rest ? Find the forces $F_1$ and $F_2$.