Question

@aaronq
. A child rolls a marble of mass m and initial speed v down a loop of track. The track includes many curves, dips, and hills. After the marble makes one complete loop around the track, its speed is 0.25v. What fraction of the marble's initial mechanical energy is lost to dissipative forces?

7/8
15/16
3/4
1/2

Answer 1

once the marble comes back around, if there were not dissipative/frictional losses, it would be moving at the same speed. that is \(\sf v_o\), but it came back with only \(\sf\dfrac{1}{4}v_o\). So, the loss is:

\(\sf E_{loss}=v_o-\dfrac{1}{4}v_o\)

Answer 2

So 3/4

Answer 3

Its 3/4 right?

Answer 4

yeah

Answer 5

Thanks

Answer 6

no problem, i'm leaving now so i can't help you with more at the moment

Answer 7

K thanks for everything