Momentum

• Rotation and Revolution Differences:

  • Rotation: An object rotates about an internal axis.

  • Revolution: An object revolves around an external axis.

Example: Should you take the outside or the inside of a merry-go-round to get the greatest speed?

Answer: Outside because you have to go a greater distance in the same amount of time as the horse on the inside.

• Linear Speed: The speed you've been talking about so far (distance divided by time.)

• Tangential Speed: the speed of something moving along a circular path, because the direction of motion is always tangent to the circle. This is linear speed but wrapped around a circle.

• Rotational Speed: (angular speed) is the number of rotations per unit of time. It is often measured in RPM. It can also be measured in angular degrees per second.

v = Tangential Speed

r = radius from center

ω = rotational speed

• Centripetal Force

  • Def: the force that is necessary to keep an object moving in a curved path and that is directed inward toward the center of rotation.

• Centrifugal Force

  • Def: a force that causes an object moving in a circular path to move out and away from the center of its path

• a = ∑F/m

• v = 2πr/T