As the blob heats up, the molecules spread apart, lowering its density.

当蜡滴加热时，分子会散开，降低其密度。

They discovered that patients with depression had a lower density of synapses than healthy people of the same age.

他们发现，抑郁症患者的突触密度低于同龄的健康人群。

Objects with lower density, like stuff that's made of organic materials, will allow more of the lower-energy X-rays to pass through.

低密度的东西，像有机材质的东西，会让低能级的X射线穿过。

Meanwhile, lighter substances with lower density, like plasma, move to its center.

与此同时， 密度较低的较轻物质，如等离子体，会移动到它的中心。

Their presence lowers the magma's density, and increases the buoyant force pushing upward through the crust.

它们的存在降低了岩浆的密度，并增加了向上推动地壳的浮力。

Therefore, when we go for a swim in the Dead Sea, our body stays afloat on account of having relatively lower density than the surrounding water.

因此，当我们在死海中游泳时，我们的身体保持漂浮状态是因为它的密度比周围的水低。

Warm water has a lower density and rises to the surface. Cold water has a higher density and therefore it sinks to the bottom.

温水具有较低的密度并上升到表面。冷水的密度较高，因此会沉到底部。

In that case, the bigger object's mass is more spread out, so we say it has lower density, where density is how much mass is inside a given volume.

在这种情况下，更大的物体的质量更分散，所以我们说它的密度更低，密度就是给定体积内的质量。