Two identical 5 kg blocks are moving with same speed of 2ms^(-1) towards each other along a frictionless horizontal surface. The two blocks collide, stick together and come to rest. Consider the two blocks as a system. Calculate work done by (i) external forces and (i) Internal forces.

Two identical 5 kg blocks are moving with same speed of 2ms^(-1) towar

1.	Two identical 5 kg blocks are moving with same speed of 2ms^(-1) towards each other along a frictionless horizontal surface. The two blocks collide, stick together and come to rest. Consider the two blocks as a system. Calculate work done by (i) external forces and (i) Internal forces.
Answer» SOLUTION :Here no external forces are acting on the system so: `vecF_("EXT")=0impliesW_("ext")=0` ACCORDING to work energy theorem: Total W.D.= Change in K.E. or `W_("ext")+W_("int")=` FINAL K.E.-Initial K.E `0+W_("int")=0-(1/2"mu"^(2)+1/2"mu"^(2))` or `W_("int")=-"mu"^(2)=-20J`