Physics behind Fear Factor –The Rotating Platform Escape

By Siyun Zou

http://www.youtube.com/watch?v=wioD2an5_xc

                  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

ω_f= ω_i + 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

F_B = ρVg = 1.70 m³ (9.8m/s²) (1000 kg/m³)

F_B = 16660 N

∑F= F_B-F_g

∑F= Vg (ρ_f – ρ_i) -ma

∑F=16660 N- (60kg*9.8m/s²)

∑F=1.6E4 N