physics
posted by Rob .
A 16kg sled is being pulled along the horizontal snowcovered ground by a horizontal force of 35 N. Starting from rest, the sled attains a speed of 2.1 m/s in 9.5 m. Find the coefficient of kinetic friction between the runners of the sled and the snow.

35  ckf * 16 = m*a
where ckf is coefficient of kinetic friction. In your textbook ckf is probably represented as the greek letter mu, but it's really hard to write greek letters here. . .
m is the mass of the sled, and a is its acceleration.
x = 1/2 * a * t^2
v = a * t
where x is the distance traveled by the sled, t is time, and v is the speed
so
9.5 = 1/2 * a * t^2
2.1 = a * t
Using algebra:
t = 2.1/a
plugging into the equation for x:
9.5 = (1/2 * 2.1^2)/a
Use algebra to solve for the acceleration, then plug into
35  ckf * 16 = 16*a
and solve for ckf