What is newton's second law of motion? forces are balanced when they are equal and opposite. an object at rest or in motion will remain at rest or in motion unless acted upon by an unbalanced force. the smaller the mass of an object, the greater the acceleration of that object when a force is applied. the greater the force applied, the greater the acceleration. every reaction is equal to the force applied.

Three different objects, all with different masses, are initially at rest at the bottom of a set of steps. each step is of uniform height . the mass of each object is a multiple of the base mass : object 1 has mass 4..00m , object 2 has mass 1..96m , and object 3 has mass . when the objects are at the bottom of the steps, define the total gravitational potential energy of the three-object system to be zero. if the objects are then relocated as shown, what is the new total potential energy of the system? each answer requires the numerical coefficient to an algebraic expression. each algebraic expression is given using some combination of the variables , , and , where is the acceleration due to gravity. enter only the numerical coefficient. (example: if the answer is 1..23mgd , just enter 1.23)

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 •  

Acoil suspended freely, points in some direction when no current is passed through it . can you tell what will happen when a current is passed though it?