If an object does work against a resistive force, what does this indicate?

When an object does work against a resistive force, such as friction or air resistance, it means that energy is being expended to overcome that force. This work done is converted into thermal energy as the resistive force transforms the mechanical energy of the object into heat. This process occurs because the resistive force opposes the motion, leading to an increase in the thermal energy of the materials involved, typically resulting in a rise in temperature.

This concept helps in understanding how energy transfers and transformations take place in physical systems. For example, if you slide an object across a surface, the energy spent to keep it moving against friction becomes thermal energy, heating up both the object and the surface.

The other options do not accurately reflect the implication of doing work against a resistive force. Energy conservation generally means that energy is not lost, only transformed, but the focus here is specifically on the conversion to heat. An increase in potential energy typically involves an object gaining height or stored energy, while a decrease in kinetic energy suggests a loss of energy without specifically indicating that work is done against a resistive force.