A stationary 4-kg shell explodes into three pieces. Two of the fragments have a mass of 1 kg each and move along the paths shown with a speed of 10 m/s. The third fragment moves upward as shown.
-What is the speed of the center of mass of this system after the explosion?
A)zero m/s
B)1 m/s
C)3 m/s
D)5 m/s
E)7 m/s

Question

A stationary 4-kg shell explodes into three pieces. Two of the fragments have a mass of 1 kg each and move along the paths shown with a speed of 10 m/s. The third fragment moves upward as shown. 
-What is the speed of the center of mass of this system after the explosion?
A)zero m/s 
B)1 m/s 
C)3 m/s 
D)5 m/s 
E)7 m/s

Quizplus · Accepted Answer

The speed of the center of mass of a system remains constant if no external forces act on it. After an explosion, the internal forces do not affect the center of mass, so its speed remains zero if it was initially at rest.

A Stationary 4-Kg Shell Explodes into Three Pieces