Net mass m =Â Â Â m1 + m2 +
m3
= 3.0Â Â Â + 4.0Â Â Â + 5.0
                        =
12 kg
   net acceleration a =   F /
m   =   19.0 / 12.0
                                                   =
1.583 m/s2
   a.   Force exerted on 5 kg
block   F =   m3 * a
                                                               =
5.0 * 1.583
                                                               =
7.915 N
b.   Force exerted
on 3 kg block   F
=Â Â Â (m2+ m3) * a
                                                               =   (4.0
+ 5.0) * 1.583
                                                               =   14.247
N
