Question

If an object is moving at `150 m/s` over a surface with a kinetic friction coefficient of `u_k=15 /g`, how much time will it take for the object to stop moving?

Answer 1

I found `10s`

Explanation:

Have a look:

Answer 2

`t=10 s`

Explanation:

`F_f=u_k*m*g`
`F_f=15/cancel(g)*m*cancel(g)`
`F_f=15m` `"friction force between object and surface"`
`"Kinetic energy of object is zero,if object stops"`
`Delta E_k=1/2*m*v^2`
`"Kinetic energy of object turns work ."`
`Delta E_k=F_f*x`
`1/2*cancel(m)*150^2=15*cancel(m)*x`
`2250cancel(0)=3cancel(0)*x`
`x=2250/3=750` `"meters"`

`x="blue area"`
`750=(150*t)/2`
`150cancel(0)=15cancel(0)*t`
`t=150/15`
`t=10 s`