Are the Forces on an Object Balanced When the Net Force Is Zero?

By Walter Unglaub

Newton's second law describes the resultant effect of having several external forces acting on an object. Find out if the forces on an object are balanced when the net force is zero with help from an experienced physics professional in this free video clip.

Transcript

Hello, my name is Walter Unglaub, and this is "Are the forces on an object balanced when the net force is zero?" Well the answer is definitely yes. And this is due to Newton's second law. So what is Newton's second law. Newton's second law describes the resultant effect of having several external forces acting on an object. It's given mathematically by the sum from one to capital N where capital N is the total number of forces acting on the object of the forces and this is equal to the net or resultant force which is equal to the mass of the object times the net or resultant acceleration. So if all of the forces on an object are balanced then the net force is going to be zero. So if this quantity is equal to zero then we have the sum of the forces is equal to zero. So this net acceleration will be zero. As an example I have a block of mass m sitting on the ground and we see that this is an inertial frame meaning that its velocity is constant. Namely zero in this case. So we have to draw the various forces that are acting on the object and we identify them as the gravitational force F of g which is equal to the mass of the object times g where this gravitational acceleration vector is pointing down and the normal force that the ground is enforcing on this mass. Keeping it in place. So what's keeping it in place it's the fact that the normal force and the weight or gravitational force are equal in magnitude but opposite in direction. So we see that all the forces are balanced and this yields a zero net force. So indeed the forces are balanced when this is zero. My name is Walter Unglaub and this is are the forces on an object balanced when the net force is zero.

About the Author

Walter Unglaub graduated from the Colorado School of Mines with a B.S. in Engineering Physics and a M.S. Applied Physics.