CORRIGES :

EXERCICE I

1. F_r.OA=F_m.OB =>

=

2. R= Fr + Fm=900+150=1050N

EXERCICE II

1.F_r=mg=0,013x9,8=0,1274N

F_m=0,0294N

F_r.L_r=F_m.L_m =>

2. F_r=mg=0,02x9,8=1,96

F_m=0,196 N

F_r.L_r=F_m.L_m =>

3. Fr/Fm=3 =>. F_r.= 3 F_m

F_r.L_r=F_m.L_m =>3 F_m L_r= F_m.L_m=>

L_m=3 L_r < =>100- L_r=3 L_r=> 100=4 L_r => L_r=25cm

EXERCICE III 

1.F_r.AO=F.OB =>

=

2. A l’équilibre,

₊

<=>F+ F_r –R=0 =>

R= F+ F_r= 150+1500=1650N

EXERCICE IV:

F_mr_m=F_rr_t =>

=

EXERCICE V :

1.F=Psin=mgsinα=50x10xsin30=500x1/2250N.

2.R=mgcosα=50x10xcos30=500xѴ3/2=433 N.