One reason could be because the ball has gotten wet from sweat, ground condensation, etc. Another reason could be because the ball has cut or gashes in it. The most common reason is to speed the game along, especially on past balls!
Haciendas used to be the Mexican equivalent to plantations and ranches. Nowadays, these no longer exist.
French money is no longer the French Franc. Nowadays it is the Euro.
A photoelectric cell, in a solar panel. Nowadays, many calculators have a miniature solar panel, to let the batteries last longer (battery power is only used when it is too dark).
Nowadays, lighthouses are usually automated, and no longer require lighthouse keepers to stay in the lighthouse.
Yes, at high speed it takes longer to change your direction, for example.Yes, at high speed it takes longer to change your direction, for example.Yes, at high speed it takes longer to change your direction, for example.Yes, at high speed it takes longer to change your direction, for example.
We no longer have dinosaurs
A longer pendulum has a longer period. A more massive pendulum has a longer period.
Change your lifestyle.
A battery can last from 1 year to many years. You change it when it no longer will start the car or when it no longer will hold a charge.
Because Christian faith no longer exists. False promises are growing thin nowadays.
Many emperors of India spred Hinduism accross and outside of India. Nowadays Hinduism no longer believes in spreading Religion.
In the MLB, umpires will bring in a new ball at their discretion. Pitchers may ask the umpire for a new ball because they don't like the current ball, or are stalling a bit. Umpires try to keep the game fair and balls get dirty with use and harder to see. They may also get nicked up when hit or when the hit the catcher's gear. These days, umpires will replace a ball if it's thrown in the dirt by the pitcher. It may stay in play longer on outs made in the field longer. For info on MLB and other baseball rules see: http://www.hitpitchcatch.com/baseball-rules-softball-rules.html#MLBBaseball