# How Is This Possible?

In the famous 1971 footage from Apollo 15, astronaut David R. Scott dropped a hammer and a feather at the same time on the surface of the Moon, thus confirming Galileo's hypothesis that gravity accelerates all objects at the same rate, regardless of mass or composition:

Undoubtedly that has been hammered into your brain since grade school. So, how do you explain this neat little video from the clever folks over at MIT:

Two wood boards are connected by a hinge. A small cup is mounted near one end of the upper board with a tee for a ball on the end. The board is lifted to a certain height, and when released the ball ends up in the plastic cup. This shows that the board has moved farther than the ball in the same period of time.

To see the video, visit the MIT News Multimedia website: Link - via Science2.0

So, the hinged plank has to travel in an arc, which is longer than the straight path that the ball falls through in order for the ball to fall into the cup. Notice that the plank hits the tabletop before the ball. Assuming air resistance doesn't come into much play (after all, the plank has more surface area than the ball) Does this mean that gravity affects the plank more than the ball? Is Galileo wrong?

It`s been said several times already, but since it`s so happily ignored:

guys, you`re all being way too difficult. The ball started higher because of the golf pin, and thus lands later. The cup started lower, and that`s how the ball ends up in the cup.
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Reference aircraft wings and the effect of displacing air around the edge of a surface. The board displaces a considerable amount of air as it falls, some of the displaced air curls around the end of the board with the ball on it (as per the end of a wing), in part aiding in propelling the ball both right (toward the cup) and counteracting some of its ability to fall- giving the impression it moves slower.

Thoguh the 'arch' hypothesis remains true, the effect would be considerably reduced in a vacuum.
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The plank is attached to the table. The pivot changes the whole plank initial vertical speed by increasing the speed of the free side.

The Galileo law works if the objects are free of any link because it would change the energy distribution.
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