Question

If an object gains mechanical energy, then a non-conservative force is:

Option 1: Doing no work
Option 2: Doing positive work
Option 3: Doing negative work
Option 4: Not relevant to the change in energy

Answer 1

When an object gains mechanical energy, it is due to a non-conservative force doing positive work on the system, as they add energy rather than convert it.

Step-by-step explanation:

When an object gains mechanical energy, it indicates that work is being added to the system. A non-conservative force is responsible for this change in energy, as conservative forces would only convert mechanical energy from one form to another without an increase in the total amount. Since the mechanical energy is increasing, the non-conservative force must be doing positive work on the object. This is because positive work is added to or transfers energy to the system, which can be seen in the example where more work is required to stop a truck compared to a mosquito, due to the truck's larger mechanical energy.