Moving an object from one place to another requires energy. The amount of energy used up is called the work. Moving an object further or with more force requires more work. W = Fd Energy is a concept! It cannot be created or destroyed, only changed from one form to another. KE, PE Applying a force to an object causes it to accelerate. A heavier object will accelerate less with the same force. With no forces acting on an object it will stay where it is or keep moving at the same speed. F = ma
US: 
