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?

2 Answers
Feb 4, 2016

Answer:

I found #10s#

Explanation:

Have a look:
enter image source here

Feb 4, 2016

Answer:

#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"#
enter image source here
#x="blue area"#
#750=(150*t)/2#
#150cancel(0)=15cancel(0)*t#
#t=150/15#
#t=10 s#