Causes. In ALS, the nerve cells that control the movement of your muscles gradually die, so your muscles progressively weaken and begin to waste away. ALS is inherited in 5 to 10 percent of cases. The other cases appear to occur randomly.
1 The smaller studio uprights usually weigh between 400 and 600 pounds. 2  The monstrous full vertical or large upright piano can weigh as much as half a ton.  A studio piano's center of gravity is also lower than a large upright's, as it is about 4 feet (1.2 m) tall as opposed to a large upright's roughly 5-foot height.
(8)Bridge. (1) Frame-also called the plate or harp, this cast iron frame supports an enormous amount of stress exerted by the strings. The average upright or medium-sized grand piano's strings have a combined pull of about 18 tons (16,300 kg).