If an object is moving at 4 m/s4ms over a surface with a kinetic friction coefficient of u_k=80 /guk=80g, how far will the object continue to move?

1 Answer
Jan 29, 2017

The object will travel only 0.10m0.10m (because a kinetic coefficient of 80/g80g is very large!)

Explanation:

This problem is most easily done by conservation of energy.
Two energy forms are involved:
A change in kinetic energy: 1/2mv_f^2-1/2mv_i^212mv2f12mv2i

Frictional heating: muF_NDelta d

The equation for conservation of energy is, in this case

1/2mv_f^2-1/2mv_i^2+mumgDelta d=0

Notice that we can divide every term by the mass m, (including the right side of the equation)

Also, v_f=0 , and inserting the values for mu, v_i and g, we get:

-1/2(4)^2+(80/g)(g)Delta d=0

Cancel the two g's

-1/2(4)^2+(80)Delta d=0

-8+80Delatd=0

80Deltad=8

Deltad=0.1m