  The electron and the proton have a negative electrostatic charge and a positive electrostatic charge respectively. Each charge-and the force associated with that unit of charge-is constant-and equal.(The electron and proton have equal, but oppositely polarized, electrostatic charges.) But there is more. The electron and the proton have a negative electrostatic charge and a positive electrostatic charge respectively. Each charge-and the force associated with that unit of charge-is constant-and equal.
The start of life for the tank did not bode well. The first model came off the factory floor on September 8th 1915. On September 10th, its track came off. The same happened on September 19th when government officials were watching.
The Army made the decision for a new tank series in 1972 and awarded developmental contracts in 1973. The first prototypes of the M1, known as the XM1, reached the testing stage in 1976, and the tank began to arrive in battalions in February 1980.