Question

use the drop - down menus to complete the sentences describing what happens when the temperature of a fluid increases.
the kinetic energy of the molecules
the speed of the molecules
the density of the fluid
the fluid

Explanation:

Step1: Kinetic energy and temperature

When a fluid is heated, the temperature increases. According to the kinetic - molecular theory, the kinetic energy of molecules is directly related to temperature. So, the kinetic energy of the molecules increases.

Step2: Molecular speed

Since kinetic energy \(K = \frac{1}{2}mv^{2}\) (where \(m\) is the mass of the molecule and \(v\) is the speed of the molecule). For a given type of molecule (\(m\) is constant), if \(K\) increases, then \(v\) (the speed of the molecules) increases.

Step3: Density of the fluid

When the molecules move faster, they tend to spread out more (assuming no change in pressure in a simple case). Density \(
ho=\frac{m}{V}\). If the volume \(V\) increases (as molecules spread out) and the mass \(m\) of the fluid (number of molecules times molecular mass) remains constant (in a closed - system, no addition or removal of molecules), then the density of the fluid decreases.

Answer:

The kinetic energy of the molecules increases. The speed of the molecules increases. The density of the fluid decreases.