I\'m so confused. Please help! A 55-kg skier skies down the smooth (frictionless
ID: 1500506 • Letter: I
Question
I'm so confused. Please help!
A 55-kg skier skies down the smooth (frictionless) ski slope illustrated in the cross-sectional diagram. She pushes off at the top with a speed of 10 m/s. At the bottom (0 m), she comes to a stop by digging her skis in sideways.
a) Construct a complete energy system diagram that could be used to
predict the speed of the skier when she is on the middle flat part (10 m).
Substitute all known values of constants and variables into the algebraic
expression of energy conservation, and identify any unknown(s). Do you have enough information to determine the speed on the middle part of the hill?
b) Construct a complete energy system diagram that could be used to predict her maximum speed just before digging in her skis at the bottom. Substitute for constants and variables and identify any unknown(s) as in part (a).
c) Assuming that the snow where she comes to a stop is at a temperature of 0° C, and that all of the kinetic energy of the skier goes into melting the snow, construct a complete energy system diagram that could be used predict the amount of snow melted by the skier while stopping. Substitute for constants and variables and identify any unknown(s) as in part (a).
side (before bouncing ermine the amount of irst momentarily stops sion of energy conser increase in thermal e 30 m - 10m > 10 m nough information to r maximum speed jusExplanation / Answer
a) Energy conservation between 10m and 30 m flat surface
So mgh1 + 0.5*m*v1^2 = mgh2 + 0.5*m*v2^2 Answer
V2 is unknown otherwise every thing is known
=> V_10 = sqrt(9.81*30 + 0.5*10^2 - 9.81*10) = 15.69 m/s Answer
b) Putting value of h2 = 0 in above equation
unknown is V_0
=> V_0 = sqrt(9.81*30 + 0.5*10^2 - 9.81*0) = 18.555 m/s Answer
c) Kinetic energy is used to melt the ice
So K.E = 0.5*m*v_0^2 = 0.5*55*18.555^2 = 9467.92 Joule
Latent heat of fussion of water = 333.55 J/g
=> m = K.E/333.55 = 9467.92/333.55 = 28.385 g Answer