A cube of side a and mass m is to be tilted at point A by applying a force F as shown in the figure. The minimum force required is

See the figure. For tilting about A the clockwise torque (due to F) should be greater than the anticlockwise torque of mg about A.mg×a2≤F3a4 ⇒F≥2mg3 ⇒Fmin=2mg3