1. Newton's second law can be written in mathematical form as \(\sum F = ma\). Within the summation of forces, \(\sum F\), ____ are(is) not included.
A. external forces
B. weight
C. internal forces
D. All of the above.
2. The equation of motion for a system of n-particles can be written as
\(\sum F_i = \sum m_i a_i = m a_G\), where \(a_G\) indicates _____
A. summation of each particle's acceleration
B. acceleration of the center of mass of the system
C. acceleration of the largest particle
D. None of the above.