Rotational Equilibrium Torque is the turning force applied to an object that usually produces rotational acceleration You use torque to turn a door handle or tighten a bolt Torque is produced when a force is applied with leverage. - an example of this is a hammer pulling out a nail

Applying Torque When you apply torque to an object you apply force perpendicular to the plain of the object An example is opening a door. - Is it easier to push a door open when pushing on the middle of the door or by the handle of the door?

The farther you push away from where the object is rotating the easier it is to push. Lever Arm is the distance from the turning point of an object to the point of contact of the force. - This is why we push doors open on the side away from the hinge of the door. This is also why a breaker bar works.

Calculating Torque Torque = Force x lever arm This means that the longer the lever arm is the more your force will be amplified.

Balanced Torques Even though different forces acting on the same rotational point the point does not have to move. - you can move each force toward or away from the rotational point to make the torque from each force equal - this is because it is the torque that rotates the object, not the force on the object.

Center of Mass Center of Mass is the spot in an object where its mass seems to be concentrated. - it is the spot on the object where its aver position of mass is located. - When an object is thrown through the air it will always rotate around its center of mass

Center of Gravity Center of gravity means the same thing as center of mass except for very large objects. - For a really tall building the gravitational pull is larger at the bottom of the building than at the top. Because of this the center of mass and the center of gravity for that building are not in the same place.

Where is the center of mass? The center of mass is not always a spot on an object. - for an empty cup the center of mass is inside the cup and does not touch the cup itself.

How to knock something over. How do you know how steep a ramp that an object can be on without tipping over? - When the center of mass of an object is above an area of support for that object then it will not tip over. - When the center of mass of an object is not above the area of support for that object then the object will tip over.

Stability Stability is how easy an object is topple. - when objects topple they change their center of gravity Unstable Equilibrium – when an object is balanced so that any motion will lower the object’s center of mass Stable Equilibrium – when an object is balanced so that any motion will raise object’s center of mass

Neutral Equilibrium – when an object is balanced so that any small movements neither raises nor lowers its center of mass

Objects in stable equilibrium have a center of gravity that raises when the object is disturbed. -this makes the object more stable and less likely to fall over -tip toes -foundation -balancing act