Which of the following is true about frictional forces?

1) They are stored as frictional potential energy.

2) They can decrease kinetic energy.

3) They produce heat potential energy.

4) They eventually convert to electromagnetic potential energy.

5) They can increase kinetic energy.

To determine which of the statements is true about frictional forces, let's analyze each statement individually:

1) They are stored as frictional potential energy.
This statement is not true. Frictional forces are not stored as potential energy. Friction is a force that results from the interaction between two surfaces in contact, resisting relative motion between them.

2) They can decrease kinetic energy.
This statement is true. Frictional forces can reduce the kinetic energy of an object in motion. When an object moves against a surface with friction, some energy is converted into heat, resulting in a decrease in the kinetic energy of the object.

3) They produce heat potential energy.
This statement is not entirely accurate. Frictional forces produce heat energy, not heat potential energy. Heat energy is a form of kinetic energy associated with the random motion of molecules within a substance.

4) They eventually convert to electromagnetic potential energy.
This statement is not true. Frictional forces do not convert directly to electromagnetic potential energy. Electromagnetic potential energy is associated with the interaction of charged particles and is not directly related to friction.

5) They can increase kinetic energy.
This statement is not true. Frictional forces always work in the opposite direction to the motion or intended motion of an object, ultimately causing a decrease in its kinetic energy.

Therefore, the true statement about frictional forces is:
2) They can decrease kinetic energy.