Question

Work done by non-conservative forces on a particle is equal to

1. Change in internal energy
2. Change in mechanical energy
3. Change in potential energy
4. ​Change in kinetic energy

Answer 1

Correct Answer - Option 2 : Change in mechanical energy

Explanation:

Non-conservative forces:

• A non-conservative force is one for which work depends on the path taken.
• Friction is an example of a non-conservative force that changes mechanical energy into thermal energy.
• Work W_nc done by a non-conservative force changes the mechanical energy of a system.
• In equation form, W_nc = ΔKE + ΔPE or, equivalently, KE_i + PE_i = W_nc + KE_f + PE_f.

 

Conservative forces:

• A conservative force is one, for which work done by or against it depends only on the starting and ending points of a motion and not on the path taken. 
• Example potential energy, gravitational force etc.