Thursday, November 29, 2012

Physics behind Fear Factor –The Rotating Platform Escape

By Siyun Zou

Fear factor is an American reality game show where a bunch of contestants compete against one another performing dangerous stunts for \$50,000. The rotating platform escape is one of the most interesting stunts.

Total moment of Inertia:
Total mass= 60kg
L=2.74 m
W= 1.22 m
I= 1/12 M (L2+W2)
I= 1/12 (60kg)(2.742 +1.222)
I= 45 kgm2
Estimated rotational Velocity of the spinning platform from video: 1 revolution per 16s
f = 0.0625 rev/sec
ω = 2πf= 2π(0.0625rev/sec)= 0.393 rad/s
The contestant took approximately 40s to set herself free from the rotating platform
ωf= ωi + αt2
0.393 rad/s= 0 + α (40s)2
α = 2.26E-4 rad/s2
Calculation of her buoyant force when she is completely submerged:
Average swimming pool volume= 375m3
Volume of the platform = (2.74m*1.22m*0.508) = 1.70 m3
FB = ρVg = 1.70 m3 (9.8m/s2) (1000 kg/m3)
FB = 16660 N
∑F= FB-Fg
∑F= Vg (ρf – ρi) -ma
∑F=16660 N- (60kg*9.8m/s2)
∑F=1.6E4 N