Two Carnot engines $A$ and $B$ are operated in succession. The first one,$A$,receives heat from a source at $T_1 = 800\, K$ and rejects heat to a sink at $T_2\, K$. The second engine,$B$,receives the heat rejected by the first engine and rejects heat to another sink at $T_3 = 300\, K$. If the work outputs of the two engines are equal,then the value of $T_2$ is ...... $K$.

$A$ man is standing on a balance and his weight is measured. If he takes a step to the left side,then his weight:

Identify $A$ and $B$ in the following reaction:
$CH_3-CH_3 \xleftarrow{B} CH_3COOH \xrightarrow{A} CH_3CH_2OH$

$A$

$B$

If $ad \neq 0$ and two of the lines represented by $ax^3+3bx^2y+3cxy^2+dy^3=0$ are perpendicular,then

Two blocks of masses $1 ~kg$ and $2 ~kg$ are connected by a metal wire going over a smooth pulley as shown in the figure. The breaking stress of the metal is $2 \times 10^9 ~N/m^2$. What should be the minimum radius of the wire used if it is not to break? Take $g = 10 ~m/s^2$.