A 2 kg block rests on a 34o incline. If the coefficient of static friction is 0.2, how much additional force, F, must be applied to keep the block from sliding down the incline?

Reaction force of inclined surface = mg cosθ

= Friction force acting in upward direction = μ x mg cosθ

If F be force required in upward direction to keep the block at rest on the plane

F + μ x mg cosθ = mg sinθ

F = mg sinθ - μ x mg cosθ

F = mg (sinθ - μ cosθ)

= 2 x 9.8 (sin34 - 0.2 cos34)

= 19.6 (.559 -.1658)

= 7.7 N

This is the minimum force required.