If during a given physical process the only force acting on an object is friction, which of the following must be assumed in regard to the object's kinetic energy? 1) decreases 2) increases 3) remains constant 4) cannot tell from the information given 5) increases up to the maximum and then remains constant

To analyze the situation where the only force acting on an object is friction, we need to consider the nature of friction and its effect on kinetic energy. 1. **Understanding Friction**: Friction is a force that opposes the motion of an object. When an object is moving and friction acts on it, it does work against the direction of motion. 2. **Effect on Kinetic Energy**: The work done by friction results in a loss of kinetic energy. As the object moves, friction will cause it to slow down, which means its speed decreases. Since kinetic energy (\(KE\)) is given by the formula: \[ KE = \frac{1}{2}mv^2 \] where \(m\) is the mass and \(v\) is the velocity of the object, a decrease in velocity will lead to a decrease in kinetic energy. 3. **Conclusion**: Since friction is the only force acting on the object, it must be assumed that the object's kinetic energy decreases over time as it continues to experience the frictional force. Thus, the correct answer is: 1) decreases.