An m=150 g block hits an M= 265 g block initially at rest on a horizontal surface. After impact they stick together and slide 7.47 m before coming to rest. The coefficient of friction between blocks and surface is 0.39.

Question

An m=150 g block hits an M= 265 g block initially at rest on a horizontal surface. After impact they stick together and slide 7.47 m before coming to rest. The coefficient of friction between blocks and surface is 0.39.
a) What is in m/s the speed of both blocks immediately after impact?

b) What is in m/s the speed of the first block (m) just before impact?

J.K · Answer

The two blocks decelerate due to friction Ffr=(m1+m2)a a=Ffr/(m1+m2) Ffr=u(m1+m2)g a=u(m1+m2)g/(m1+m2) cancelling the common parameter,a=ug a=0.39*10=3.9m/s Vf=sqrt(2*3.9*7.47)=7.63m/s b)150v1=(150+265)*7.63 v1=21.1m/s