To test the performance of its tires, a car

travels along a perfectly flat (no banking) cir-

cular track of radius 516 m. The car increases

its speed at uniform rate of

at ≡d |v|÷dt = 3.89 m/s^2

until the tires start to skid.

If the tires start to skid when the car reaches

a speed of 32.8 m/s, what is the coefficient of

static friction between the tires and the road? The acceleration of gravity is 9.8 m/s^2​

Respuesta :

Answer:

The coefficient of  static friction between the tires and the road is 1.987

Explanation:

Given:

Radius of the track, r =  516 m

Tangential Acceleration [tex]a_r[/tex]=  3.89 m/s^2

Speed,v =  32.8 m/s

To Find:

The coefficient of  static friction between the tires and the road = ?

Solution:

The radial Acceleration is given by,

[tex]a_{R = \frac{v^2}{r}[/tex]

[tex]a_{R = \frac{(32.8)^2}{516}[/tex]

[tex]a_{R = \frac{(1075.84)}{516}[/tex]

[tex]a_{R = 2.085 m/s^2[/tex]

Now the total acceleration is

[tex]\text{ total acceleration} = \sqrt{\text{(tangential acceleration)}^2 +{\text{(Radial acceleration)}^2[/tex]

=>[tex]= \sqrt{ (a_r)^2+(a_R)^2}[/tex]

=>[tex] \sqrt{ (3.89 )^2+( 2.085)^2}[/tex]

=>[tex] \sqrt{ (15.1321)+(4.347)^2}[/tex]

=>[tex]19.4791 m/s^2[/tex]

The frictional force on the car will be f = ma------------(1)

And the force due to gravity is W = mg--------------------(2)

Now the coefficient of  static friction is

[tex]\mu =\frac{f}{W}[/tex]

From (1) and (2)

[tex]\mu =\frac{ma}{mg}[/tex]

[tex]\mu =\frac{a}{g}[/tex]

Substituting the values, we get

[tex]\mu =\frac{19.4791}{9.8}[/tex]

[tex]\mu =1.987[/tex]