7. How does friction affect the kinetic energy of an object?

Friction is a resistive force to motion. When two bodies move against each other some of the kinetic energy is converted to heat energy due to friction. This reduces the total kinetic energy in the system ... Mechanical energy is reduced due to friction and converted to heat.

Explanation:

Kinetic friction does oppose the relative motion of two surfaces. If the one of these surfaces is stationary, then it will tend to slow down the moving object.