Work is done only when a force causes an object to move. The motion of objects is usually opposed by _______, which removes energy from the system.

A.

heat

B.

friction

C.

inertia

D.

gravity

Question

Work is done only when a force causes an object to move. The motion of objects is usually opposed by _______, which removes energy from the system.






  A. 

heat 
  
  B. 

friction 
  
  C. 

inertia 
  
  D. 

gravity

ybarrap · Answer

"Opposing" the motion implies a force. Only one of your options is a force. 

Gravity is acceleration, inertia concerns the tendency of objects to continue moving, heat is energy, friction is a force that goes against the motion of an object