Public School, Deer Creek Minnesota, 1918 LakesnWoods.com Postcard and Postcard Image Collection - click image to enlarge Aerial view, Deer Creek Minnesota, 1972
Whenever work is done upon an object by an external force, there will be a change in the total mechanical energy of the object. If only internal forces are doing work (no work done by external forces), there is no change in total mechanical energy; the total mechanical energy is said to be conserved.
The net force is the total force. It could be the sum of two forces or more than two forces. If only one force acts upon an object, then this one force would be the net force. If the net force on an object is zero, then the object experiences no velocity change.If the net force on an object is not zero, then the object will show a change in velocity. Lastly, this net force must be external to the object. The net force can not come from the object itself.he First Law is concerned with changes in velocity caused by non-zero net forces. Isaac Newton stated three laws of motion; the first law deals with forces and changes in velocity. For just a moment, let us imagine that you can apply only one force to an object.