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will a container with marbles or a container with tennis balls overflow first if water was poured in at the same time
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From Wikipedia, https://en.wikipedia.org/wiki/Marble_(toy)
A marble is a small spherical toy usually made from glass, clay, steel, plastic or agate.
These balls vary in size. Most commonly, they are about 1 cm (1⁄2 in) in diameter, but they may range from less
than 1 mm (1⁄30 in) to over 8 cm (3 in), while some art glass marbles for display purposes are over 30 cm (12 in) wide.
A container filled with marbles of different/various sizes will have lower porosity comparing with a container filled
with tennis balls (all of the same size).
In other words, the free (void) volume in a container filled with marbles is lesser than that in a container filled with tennis balls.
Therefore, the first container will be filled with water faster than the second.
Though, if the marbles in the container are all of the same size, then the filling time will be the same for both containers,
because the void volume will be the same.