Conservation of Energy Ranking Task

Six pendulums of various masses m are released from various heights h above a tabletop, as shown in the figures below. All the pendulums have the same length and are mounted such that at the vertical position their lowest points are the height of the tabletop and just do not strike the tabletop when released. Assume that the size of each bob is negligible.

A) Rank each pendulum on the basis of its initial gravitational potential energy (before being released).

a) m=8 kg; h=15 cm;                                  U = (8)(9.8)(0.15) = 11.76 J

b) m=1 kg; h=60cm;                                  U = (1)(9.8)(0.6) = 5.88 J

c) m=2 kg; h=60 cm                                   U = (2)(9.8)(0.6) = 11.76 J

d) m=3 kg; h=45 cm;                                  U = (3)(9.8)(0.45) = 13.23 J

e) m=4 kg; h=30 cm;                                  U = (4)(9.8)(0.3) = 11.76 J

f) m=2 kg; h=30 cm:                                   U = (2)(9.8)(0.3) = 5.88 J

=>

From largest to smallest: d, (a,c,d), (b,f)

B) Rank each pendulum on the basis of the maximum kinetic energy it attains after release.

h = |45, m=3|  >  |m=2, h=60| , |m=4, h=30| ,  |m=8, h=15|  > |m=2, h=30| , |m=1, h=60|

C) Rank each pendulum on the basis of its maximum speed.

Comments

2 responses to “Conservation of Energy Ranking Task”

  1. Bill Avatar
    Bill

    Number two is completely wrong

  2. JD Avatar
    JD

    Bill, look again its right if you overlap them

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