The mass per unit length of a 14-gauge copper wire is 18.5 g/m. If the wire is placed running along the horizontal x-axis (east-west) in a region in which there is a uniform 0.423-T magnetic field directed along the horizontal y-axis (northward). Calculate the magnitude of the minimum current in the wire that could cause the wire to levitate (i. e., have the force of its own weight canceled by a vertically upward magnetic force on it.)

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

Imagine that you have two balloons (or, better yet, actually inflate two balloons, if possible). create static electricity around one of the balloons by rubbing it against your hair or your sweater and then bring that balloon close to the other balloon, which has not been charged. try this with at least one other object—and for variety in the discussion, avoid using an object already described by your classmates. then, for your initial post to the discussion, answer the following questions: what happened with the two balloons?