school
Acemy

Conservation of Angular Momentum

AP Physics 1· difficulty 4/5

A bullet of mass mm moves horizontally with speed vv and embeds itself in the end of a uniform rod of length LL and mass MM that hangs vertically and pivots about its top end (Irod=13ML2I_{\text{rod}} = \tfrac{1}{3}ML^2). Immediately after the collision, what is the angular speed of the rod-bullet system?

  • A

    ω=mv/(13ML)\omega = m v /(\tfrac{1}{3}M L)

  • B

    ω=mvL/(13ML2+mL2)\omega = m v L /(\tfrac{1}{3}M L^2 + m L^2)

    check_circle
  • C

    ω=mv/(ML+mL)\omega = m v /(M L + m L)

  • D

    ω=v/L\omega = v / L

Explanation

Conserve angular momentum about the pivot: Li=mvLL_i = m v L and Lf=(Irod+mL2)ωL_f = (I_{\text{rod}} + m L^2)\omega. Solving gives ω=mvL/(13ML2+mL2)\omega = m v L /(\tfrac{1}{3}M L^2 + m L^2).

Want 10 more like this — adaptive to your weak spots?

Practice 10 like thisarrow_forwardPredict my AP score

Related questions

auto_awesomeAll Toolsquestion_answerHomework Q&Amenu_bookAP & SAT PreptimelineLearn Mode