physics
posted by Anonymous .
A hockey puck struck by a hockey stick is given an initial speed v0 in the positive xdirection. The coefficient of kinetic friction between the ice and the puck is μk.
(a) Obtain an expression for the acceleration of the puck. (Use the following as necessary: μk and g.)
a =
(b) Use the result of part (a) to obtain an expression for the distance d the puck slides. The answer should be in terms of the variables v0, μk, and g only.
d =

f = ma
μk * f(normal) = m*a
μk *m*g = m*a
μk *g =a
so a = μk*g
this is defined to be a negative acceleration since the friction force works in the opposite direction to the movement of the puck
vFinal = v0 + at
so t = (vFv0)/a
d = t*(vF+v0)/2
so d = (vF+v0)(vFv0)/2a
substitute in our 'known' values: a = μk*g, and vF = 0 (since the puck has stopped sliding)
d = (0+v0)(0v0)/ 2(μk*g)
d = v0^2 / (2μk*g)
(eliminate negatives as d is positive)