A block of 20 kg mass rests on a flat horizontal surface. If the coefficient of static friction between the block and the surface is 1/4, the horizontal force 'F' which will cause the block to start moving is approximately given by (take g = 10 m/s2):

The magnitude and direction of the acceleration produced in a body of mass 5 kg when two mutually perpendicular forces 8 N and 6 N act on it, are respectively:

Two blocks of masses 3 kg and 1 kg are placed in contact on a smooth horizontal surface. A horizontal force F = 5 N is applied on the 3 kg block from the left. Find the contact force exerted between the two bodies.