# Coefficient of kinetic friction between box and floor

## Homework Statement

A 98 N box of oranges is being pushed across a horizontal clean steel surface until it stops. As it moves, it is slowing down at a constant rate of 1.1m/s each second. The push force has a horizontal component of 25N and a vertical component of 20N downward. Calculate the coefficient of kinetic friction between the box and the floor.

## The Attempt at a Solution

summation of Fx = 25N - fk = ma
= 25N - fk = (10kg)(1.1m/s^2)
fk = 14N???
summation of Fy= 0 = -Fw - Fdown +normal force
normal force = 20N + 98N = 118N???

fk = (uk)(Fn)
(14N / 118N) = uk
uk = 0.119

## Answers and Replies

PhanthomJay
Homework Helper
Gold Member
You're on the right track, but not quite there yet. The box is slowing down. What's the direction of the acceleration and the net horizontal force acting on the box?

thanks phantomjay
summation of Fx = 25N - fk = ma
= 25N - fk = (10kg)(-1.1m/s^2)
fk = (1.1m/s^2)(10kg) +25N
fk = 36N

uk = (36N/118N)
uk = 0.305

is this right?

PhanthomJay