Further informationson the exhibit "Viscosity of liquids"
The balls are pulled down by gravity. The speed at which the balls arrive at the bottom, however, depends on the weight of the balls and the density of the liquid through which the balls sink to the bottom.
Since in this case both balls are identical, the density of the liquids is decisive. The density of a body is the ratio of its mass to its volume. Density means whether a body is as light as a feather or as heavy as a piece of iron in relation to its size.
The yellow liquid has a lower density than the orange one. The ball in the yellow liquid can therefore sink to the ground more quickly because the resistance of the liquid is lower than that of the orange liquid. With the orange liquid the speed with which the ball sinks to the ground is slowed down by the higher density of the liquid. Thus it arrives on the ground only after the ball in the yellow liquid.