a) G = m×g = 10N
Gt = G×sinα = 10 × sin30° = 5N
Gn = G×cosα = 10 × cos30° = 5√3N
b) Gt-Ff = m×a => a = (Gt-Ff)/m
Ff = miu × m × g = 0.4 × 1 × 10 = 4N
Din primele doua relatii => Ff = (5-4)/1 = 1N
c) Coboara uniform, deci acceleratia este 0
F+Ff-Gt=0 => F = Gt - Ff = 1N
d) Urca uniform, deci acceleratia este 0
F'-Ff-Gt = 0 => F' = Ff+Gt = 9N
