Exam 2

Exam 2

1. CH 5: Circular Motion and Gravitation

   • period of motion =T= (2 pi r)/v
     • centripetal acceleration = ac = (v^2)/r
       • spinning rate = w = v/r
   • used in many cases
     • planet orbits, satellite orbits
     • theme park ride: turns, loops and hills

2. CH 6: Work and Energy

   • Work= Force multiplied by the difference of x multiplied by cos of the angle
     • Work is measure in Joules (J)
     • W= Fxcos(angle)
   • Energy: Kinetic and Potential
     • Kinetic Energy (KE)= 1/2 mv^2
     • Potential Energy (PE)= mgh
     • Mechanical Energy= mgh + 1/2 mv^2
   • E1 = E2
   • KEi + PEi = KEf + PEf

3. CH 8: Rotational Motion

   • Exam 1
   • Describing rotational motion
     • Rotational Quantities
       • Angular position = theta
         • theta = (s/r) where s is arc length, r is radius
       • Angular velocity = lowercase omega (fancy w)
         • omega = theta/time
       • Angular acceleration = alpha
         • alpha = omega/time
     • Radians
       • 360 degrees = 2(pi) rad
   • Torque and Newton's Laws for rotational motion
     • torque = Force * radius
     • sigma torque = I * alpha
       • moment of inertia = I = dependent upon object and shape
       • Newton's second law for rotational motion
   • Rotational Equilibrium
     • total torque = 0
   • Rotational Dynamics
     • delta theta = (angular velocity)(delta time) + 1/2(alpha)(delta time ^2)
       • final angular velocity = (initial ang velocity) + (alpha)(delta time)
     • (ang velocity final ^2) = (ang velocity initial ^2) + 2(alpha)(delta theta)
   • Combined Rotational and Translational Motion
     • Arises in many cases
       • a rolling wheel
       • motion of a baseball bat
     • Rolling Motion
       • angular v * R = v = 2(pi)R / T
       • a = alpha * R
     • base ball bat scenario
       • more complex than rolling motion
         • involves linear and rotational:
           • quantities, dynamics, and center of mass

4. Chapter 7 - Momentum, impulse, and collisions

   • Momentum
     • Momentum(P) = mass x velocity
     • Momentum is conserved during collisions
   • Impulse
     • Impulse is the change in time multiplied by the force in question. This is the same as the change in momentum.
   • Collisions
     • Elastic collisions
       • Kinetic energy is conserved
       • KE1f+KE2f = KEi1+KEi2
       • momentum is conserved
     • Inelastic collisions
       • Kinetic energy is not conserved
       • KE1f+KE2f not equal to KE1i+KE2i
       • Vf = (m1v1i + m2v2i)/(m1+m2)
       • momentum is conserved
     • Kinetic energy = 1/2 mv
     • completely inelastic collisions
       • objects stick together after collisions
         • momentum still conserved