Question

question 15 (1 point)
if the net work done on an object is zero, then the objects kinetic energy
decreases.
remains the same.
increases.
is zero.
question 16 (1 point)
can work be done on a system if there is no motion?
yes, if an outside force is provided.
yes, since motion is only relative.
no, since a system which is not moving has no energy.
no, because of the way work is defined.
question 17 (1 point)
it is a well - known fact that water has a higher specific heat capacity than iron. now

Explanation:

Question 15

The work - energy theorem states that the net work done on an object, \(W_{net}\), is equal to the change in the object's kinetic energy, \(\Delta KE\). Mathematically, \(W_{net}=\Delta KE = KE_{final}-KE_{initial}\). If the net work done on an object (\(W_{net} = 0\)), then \(KE_{final}-KE_{initial}=0\), which means \(KE_{final}=KE_{initial}\). So the object's kinetic energy remains the same.

Work is defined as the product of the force applied (\(F\)) and the displacement (\(d\)) of the object in the direction of the force, \(W = F\times d\times\cos\theta\) (where \(\theta\) is the angle between the force and displacement vectors). If there is no motion, then the displacement \(d = 0\). Substituting \(d = 0\) into the work formula, we get \(W=0\). So work cannot be done on a system if there is no motion, because of the way work is defined.

Answer:

B. remains the same.

Question 16