Center of MassBalance

Center of Mass

• The center of mass (labeled c.g. in the picture next to this) is the point of balance where all the weight is concentrated.

• It is located at the objects average position of weight

Center of Mass

• Binary Stars have a center of mass between the stars.

• They orbit the center of mass as they go around.

• Sometimes the center of mass is inside one of the stars, like for the Earth-Sun system

Center of Mass

Answer #1 on the worksheet with me using the formula below

TorqueTwerking has a lot to do with Torque

TORQUE

• Torque is different from force. The units are N m (Newton meter)⋅

• Force makes objects accelerate, while torque makes objects rotate

• A torque is produced when a force is applied with leverage

• This leverage makes an object rotate

TORQUE• Torque = Force x distance x

sin(angle)

• The further you apply the force from the center of rotation, the more torque you apply

• For the maximum torque, you must apply forces perpendicular to the lever arm

TORQUE

• Example: A rod that is 8.0 meters in length applies a force of 600 N on a rock at 60° in order to lift it. How much torque does it apply?

TORQUE

• You can apply torque from multiple directions. You will have to add the torques by direction.

• This seesaw is balanced, but the distance of the small guy from the center is unknown….

TORQUE• Clockwise motion is considered to be negative

• Counterclockwise motion is considered to be positive

TORQUE

• A uneven single blade on a pin is unbalanced by two forces. One force of 100N is applied from the bottom at 0.7m to the left side, and another force of 70N is applied 0.5m to the right side. What is the resultant torque?

TORQUE

• Try the second problem on the worksheet by yourself

• The Homework is…. This worksheet I am passing out…

• DUE 10/13/15