Physics 1 - Solving Problems Using Newton's Laws: Ropes and Tension

After watching our videos on Newton's laws, it's a good time to start looking at how to use these laws to solve physics problems. Today's free Physics 1 lecture begins with a demonstration of tension with a rope. As we know, forces are pushes or pulls. Tension is a stretching or staining force, a good example being the force applied to a rope. The greater the tension, the more force on the rope.

Professor Pollock then shows that if a rope is massless, the net force on it is zero because the force on one end of the rope is equal in magnitude and opposite in direction to the force on the other end of the rope. Whew! You'll see exactly how this works when Prof. Pollock proves it using the F=ma equation from Newton's second law. He'll then demonstrate how pulleys change the direction, but not the magnitude of forces on ropes.

Professor Pollock also provides a good method of solving any problem using Newton's second law: drawing a force diagram. Creating a force diagram involves drawing the situation and noting all sources of force on the object.