When a person ice skates, the surface of the ice actuallymelts beneath the blades, so that he or she skates on a thinsheet of water between the blade and the ice.( a ) Find an expression for total friction force on the bottomof the blade as a function of skater velocity V , bladelength L , water thickness (between the blade and theice) h , water viscosity μ , and blade width W .( b ) Suppose an ice skater of total mass m is skatingalong at a constant speed of V 0 when she suddenlystands stiff with her skates pointed directly forward,allowing herself to coast to a stop. Neglecting frictiondue to air resistance, how far will she travelbefore she comes to a stop? (Remember, she iscoasting on two skate blades.) Give your answer forthe total distance traveled, x , as a function of V 0 , m ,L , h , μ , and W .( c ) Find x for the case where V 0 = 4.0 m/s, m = 100 kg,L = 30 cm, W = 5.0 mm, and h = 0.10 mm. Do youthink our assumption of negligible air resistance is agood one?
When a person ice skates, the surface of the ice actually
melts beneath the blades, so that he or she skates on a thin
sheet of water between the blade and the ice.
( a ) Find an expression for total friction force on the bottom
of the blade as a function of skater velocity V , blade
length L , water thickness (between the blade and the
ice) h , water viscosity μ , and blade width W .
( b ) Suppose an ice skater of total mass m is skating
along at a constant speed of V 0 when she suddenly
stands stiff with her skates pointed directly forward,
allowing herself to coast to a stop. Neglecting friction
due to air resistance, how far will she travel
before she comes to a stop? (Remember, she is
coasting on two skate blades.) Give your answer for
the total distance traveled, x , as a function of V 0 , m ,
L , h , μ , and W .
( c ) Find x for the case where V 0 = 4.0 m/s, m = 100 kg,
L = 30 cm, W = 5.0 mm, and h = 0.10 mm. Do you
think our assumption of negligible air resistance is a
good one?
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