Question

If an object is moving at `15 m/s` over a surface with a kinetic friction coefficient of `u_k=225 /g`, how far will the object continue to move?

Answer 1

The distance is `=0.5m`

Explanation:

Kinetic friction is

`F_k=mu_k*N`

Normal reaction `=Ng`

`N=mg`

So,

`F_k=mu_k*mg`

Bu Newton's second Law

`F=ma`

`-F_k=-mu_kmg=ma`

`a=-mu_kg`

`a=-225/g*g=-225ms^2`

The negative sign indicates that this is a deceleration

Now, we apply the equation of motion

`v^2=u^2+2as`

`v=0`

`2as=-u^2=-15^2=-225`

`s=-225/-225*1/2=0.5m`