Question

The work-energy theorem is valid for positive work done.

• A. true

Answer 1

Answer: (A)

True

Answer 2

The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy. Mathematically, this is expressed as:

$W_{net} = \Delta K = K_f - K_i$

where $W_{net}$ is the net work done on the object, $K_f$ is the final kinetic energy, and $K_i$ is the initial kinetic energy.

Work done can be positive, negative, or zero:

1. Positive Work Done ($W_{net} > 0$): If the net work done on an object is positive, its kinetic energy increases ($\Delta K > 0$, so $K_f > K_i$). The work-energy theorem accurately describes this situation.

2. Negative Work Done ($W_{net} < 0$): If the net work done on an object is negative, its kinetic energy decreases ($\Delta K < 0$, so $K_f < K_i$). The work-energy theorem also accurately describes this situation.

3. Zero Work Done ($W_{net} = 0$): If the net work done on an object is zero, its kinetic energy remains constant ($\Delta K = 0$, so $K_f = K_i$). The work-energy theorem holds true in this case as well.

The statement "The work-energy theorem is valid for positive work done" means that the theorem correctly applies when positive work is done on an object. As shown in point 1 above, this is true. The theorem does not fail or become invalid when positive work is done.

The statement does not claim that the work-energy theorem is only valid for positive work done. It simply states that it is valid for positive work done. Since the theorem indeed applies correctly in cases of positive work, the statement is true.