# College Physics - Speed

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Traveling at a speed of 15.6 m/s, the driver of an automobile suddenly locks the wheels by slamming on the brakes. The coefficient of kinetic friction between the tires and the road is 0.730. What is the speed of the automobile after 1.25 s have elapsed? Ignore the effects of air resistance.

• College Physics - Speed - ,

Vf=Vi+at where a= forcefriction/mass= .730*mg/m= .730g

• College Physics - Speed - ,

I don't have mass so I can't use this formula :(

• College Physics - Speed - ,

good grief.

.730mg divided by m is .730g

• College Physics - Speed - ,

No matter how I use the formula you provided I do not get the correct answer of: 6.66 m/s.

• College Physics - Speed - ,

You may want to drop physics.
15.6-.730*9.8*1.25=
which is
Vf-mu*g*1.25

• College Physics - Speed - ,

Thanks for your help bobpursley. However, your advise was unwarranted. Just because someone needs additional help understanding a concept doesn't mean they should "drop" out of a class. Jiskha is a learning environment for those seeking help to better understand ideas and concepts please remember that.