In the following circuit, the equivalent resistance between X and Y is ...... \( \Omega \):

According to the given figure, X is at a lower potential with respect to Y. Hence, both diodes are in reverse biasing, so the equivalent circuit can be redrawn as follows:

Equivalent Resistance Calculation:
\[ R_{{eq}} = 8 + 2 + 6 = 16\Omega \]
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)): 