Your 3.10 kg physics book is next to you on the horizontal seat of your car. The

Question

Your 3.10 kg physics book is next to you on the horizontal seat of your car. The coefficient of static friction between the book and the seat is 0.600, and the coefficient of kinetic friction is 0.500. Suppose you are traveling at 61.2 km/h = 17.0 m/s and brake at a constant rate to a stop over a distance of 46.5 m. (a) Will the book start to slide over the seat? yes no Correct: Your answer is correct. (b) What force does the seat exert on the book in this process? WebAssign will check your answer for the correct number of significant figures. upward and backward at WebAssign will check your answer for the correct number of significant figures. ° with the horizontal. I alreday established the book will slide off the seat but how do i do part b???

Explanation / Answer

Relevant equations
F=N
F=m * ax
N= mg= m * ay

The attempt at a solution

I know:
m=3.10g
s=0.6
k=0.5
Vi=61.2 km/h=17.0m/s
Vf=0
x=46.5m

Well, coefficient of static friction means stationary and coefficient of kinetic friction means moving. Since in this case
s>k,

that means that the book is stationary.
So part a is no, because the static friction is greater than the kinetic friction.

According to Newton's first law, objects in motion stays in motion and objects at rest stays at rest (stays in motion unless acted upon by another force). I think that if the acceleration increases, the book will start to move, for
k will start to increase.

First, you must find the acceleration of the car. So, how would you find that?

Well, you have Vi = 17.0 m/s and Vf = =0.00 m/s.

You also know that deta x is 46.5m.

So, in order to find the acceleration of the car, you would use the equation.....

Vf2 = vi2 + 2 * a * ddelta x

So your acceleration by putting all values is - 3.10 m/s2

I use the equation f=N
f=-w+N
w=N
w=mg or N=mg
F=*mg
F=0.6(3.10)(-9.8)=-18.2
So, the books would have to overcome 18.2 static friction before the books can slide over the seat.

I found that the acceleration is -3.107m/s2.
And to find the maximal friction force I would use the equation, F=ma.
F=(3.10) (3.107) = - 9.63N

That's the force needed.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.