Dimensional Analysis. Dimensional Analysis (also called Factor-Label Method or the Unit Factor Method) is a problem-solving method that uses the fact that any number or expression can be multiplied by one without changing its value. It is a useful technique.
In 1887, the first dry cell battery was invented. Unlike previous batteries, it used a paste electrolyte instead of a liquid.
The first cellular phone was invented and demonstrated in 1973 by Martin Cooper, an engineer and general manager for Motorola, who successfully developed a portable handset using cellular communications technology. Cooper made the first ever cellular phone call in April 1973 using the prototype Motorola Dyna-Tac.However, Cooper's first cellphone was the result of decades of research and development into mobile radio communications, and cellphones would not be widely used until 20 years after the Dyna-Tac.ooper made the first ever cellular phone call in April 1973 using the prototype Motorola Dyna-Tac. However, Cooper's first cellphone was the result of decades of research and development into mobile radio communications, and cellphones would not be widely used until 20 years after the Dyna-Tac.