oat physics unit 6

triple six by zylenox

rotational motion variables

• Angle of rotation (angular displacement)

  • Δθ = Δs/r

  • 1 rad = 180/π^o

• Angular velocity

  • ω = Δθ / Δt

• Tangential velocity

  • v_tan = ωr

rotational motion equations

angular momentum

A vector quantity that represents the tendency of a rotating object to keep rotating about its axis.

• Conserved quantity when net external torque is 0.

• L = Iω

moment of inertia

An object's tendency to resist motion (higher = harder to rotate object). 

• Cylinder: I = ½mr²

• Sphere: I = ⅖mr²

• Hoop: I = mr²

• Rolling down hill speed: Hoop > cylinder > sphere

rotational kinetic energy

• KE_rot = ½Iω²

  • I = moment of inertia

  • ω = angular velocity

• Total work = ΔKE_rot

centripetal acceleration

acceleration that is directed toward the center of a circular path. It keeps the object moving in a circle.

• a_c = v²/r

• a_c = rω²

centripetal force

any force that causes an object to travel in a circular path. It is at a 90^o angle to the tangential velocity.

gravitational force

the force of attraction between any two bodies.

• F_G = (Gm₁m₂)/r²

• G = gravitational constant = 6.67E-11

• m₁ and m₂ = mass of two objects

• r = distance between the centers of the two objects.

mass vs weight

• Mass: A measure of how much matter is in a physical object.

• Weight: The gravitational force exerted on an object of a certain mass. F = mg.

acceleration due to gravity

• For any planet: g = (GM_p)/(R_p²)

• ^ Gravitational constant, mass of planet, radius of planet

escape velocity

the lowest velocity an object must have to escape the gravitational pull of a planet. It is independent of the mass of the object.

poop filled rotator cuff

it just happens sometimes, but shoulder stretches can get the poop outta there