P2. A skier of mass m 75 kg travels along the path shown in the figure. He start

Question

P2. A skier of mass m 75 kg travels along the path shown in the figure. He starts at point A with velocity vA 5.0 m/s. Over the part of the path between points B and C the snow is slushy and the coefficient of kinetic friction pu; between the snow and the skier is 0.12. Friction can be ignored for the rest of the path a. (8) Determine the velocity?Bofthe skier at point B b. (8) The distance L between B and C is 20 m. Calculate the work W done by friction on the skier between points B and C c. (9) Calculate the velocity vo of the skier at point C H 10.0 m h 4.0 m Windows 8

Explanation / Answer

(a)

Use the conservation of energy

m*g*H + 1/2*m*vA2 = m*g*h + 1/2*m*vB2

vB2 = 2*g*H +vA2 - 2*g*h

vB2 = 2*9.8*10 + 25 - 2*9.8*4

vB = 11.94 m/s

(b)

work done by the friction

Wf = uk*m*g*L

Wf = 0.12*75*9.8*20

Wf = 1764 J

(c)

the velocity is

1/2*m*vc2 + mgh = mgh+1/2*m*vB2 -Wf

1/2*m*vc2 = /2*m*vB2 -Wf

vc2 = vB2 - 2*Wf/m

vc2 = (11.94)2 - 2*1764/75

vc = 9.72 m/s

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