Question

If the sum of an object's kinetic energy (KE) and potential energy (PE) is constant, then:

Option 1: Non-conservative forces are doing work
Option 2: Non-conservative forces are not doing work
Option 3: The object is stationary
Option 4: The object has no energy

Answer 1

If the sum of an object's kinetic energy (KE) and potential energy (PE) is constant, it means that non-conservative forces are not doing work.

Step-by-step explanation:

If the sum of an object's kinetic energy (KE) and potential energy (PE) is constant, it means that all energies involved in the system are balanced and there is no net change in total mechanical energy. This can only happen if the work done by non-conservative forces is zero. Therefore, option 2: Non-conservative forces are not doing work is the correct answer.