a pitcher throws a ball, what is work in physics?

Question

A pitcher throws a ball at 90 mph and the catcher stops it in her glovea. Is the work done on the ball by the pitcher positive, negative, or zero?b. Is the work done on the ball by the catcher positive, negative, or zero?

Hermina Ferry · Accepted Answer

The pitcher takes the ball from having basically no kinetic energy to having a large kinetic energy. Thus, the pitcher does positive work on the ball.The catcher does just the opposite, and does negative work on the ball.=== Edit ===Nice try, John, but are you saying that scalars can't be negative? Are you also saying that one cannot extract energy from another system (work done by the system on you is positive, but work done by you on the system is negative)?Are you also saying that local conservation of energy doesn't hold? If not, then where does the energy of the moving baseball go?Finally, are you saying that dot products (the integrand in the link you sent) can't be negative?🙂

Hermina Ferry · Answer

Pitcher is doing positive work, catcher doing negative.Pitcher makes ball move, hence direction, catcher, in turn, decelerates the motion causing negative work since the subject is the ball.

Hermina Ferry · Answer

Nice try Flutpah but see ref belowWork is a scalar quantityPitcher does work (force * distance) in accelerating the ballCatcher does work (force * distance) in decelerating it!both positive.

Jakob Littel

a pitcher throws a ball, what is work in physics?

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