Answer:
To pull the board out from under the weight, you must overcome the static friction between the board and the table. The static friction force is given by:
F_friction = μ * F_normal
where F_friction is the friction force, μ is the coefficient of friction, and F_normal is the normal force, which is the force perpendicular to the surface of the board and table.
In this case, the normal force is the weight of the board plus the weight of the weight on top of it, which is 1 kg + 2 kg = 3 kg. Therefore, the normal force is 3 kg * 10 m/s^2 = 30 N.
Plugging this into the equation for static friction, we get:
F_friction = 0.5 * 30 N = 15 N
This means that you must apply a force of at least 15 N to the board in order to pull it out from under the weight.
Hope this helps! ^_^