Question

which equation represents the law of conservation of energy in a closed system?
○ (ke_{i}+pe_{i}=ke_{f}+pe_{f})
○ (pe_{i}+pe_{f}=ke_{i}+ke_{f})
○ (ke_{i}-ke_{f}=pe_{i}-pe_{f})
○ (ke_{i}-pe_{f}=pe_{i}-ke_{f})

Explanation:

Step1: Recall energy - conservation concept

In a closed system, total mechanical energy is conserved.

Step2: Identify mechanical - energy components

Mechanical energy is sum of kinetic energy ($KE$) and potential energy ($PE$).

Step3: Determine initial and final states

Initial total mechanical energy is $KE_i + PE_i$, final is $KE_f + PE_f$. They are equal due to conservation.

Answer:

$KE_i + PE_i=KE_f + PE_f$