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A truck using a rope to tow a 2230-kg car accelerates from rest to 13.0 m/s in a time of 15.0s. How strong must the rope be? μk = 0.373

Respuesta :

Answer:

The rope must have a force of 10084,21 N

Explanation

Acceleration calculation

The car acceleration is equal to the acceleration of the truck

ac: car acceleration[tex]\frac{m}{s^{2} }[/tex]

at: truck acceleration[tex]\frac{m}{s^{2} }[/tex])

[tex]ac = at= \frac{vf-vi}{t-ti}[/tex]  equation(1)

Known information:

vi = Initial speed = 0, ti = initial time = 0

vf = Final speed = 13 [tex]\frac{m}{s}[/tex], t = final time =5 s

We replaced the known information in the equation(1):

[tex]ac = at = \frac{13-0}{15-0} [/tex]

[tex]ac=ac=\frac{13}{15}  \frac{m}{s}[/tex]

Dynamic analysis

The forces acting on the car are the following:

Wc: Car weight

N: normal force, road force on the car

Ff: Friction force

T: Force of tension

Car weight calculation:

[tex]Wc=mc*g[/tex]

mc = Car mass = 2230kg

g = Gravity acceleration=9.8 [tex]\frac{m}{s^{2} }[/tex]

[tex]Wc= 2230*9.8[/tex]

[tex]Wc=21854 N[/tex]

Normal force calculation:

Newton's first law

[tex]sum Fy= 0[/tex]

[tex]N-W=0[/tex]

[tex]N=W[/tex]

[tex]N=21854 N[/tex]

Friction force calculation (Ff):

We have the formula to calculate the friction force:

Ff = μk * N  Equation (3)

μk kinetic coefficient of friction

We know that μk = 0.373and N= 21854N ,then:

[tex]Ff=0.373*21854[/tex]

[tex]Ff=8151.54 N[/tex]

Calculation of the tension force in the rope (T):

Newton's Second law

[tex] sum Fx= mc*ac[/tex]

[tex]T-Ff=mc*ac[/tex]

[tex]T=2230(\frac{13}{15}) + 8151.54[/tex]

T=10084,21 N

Answer: The rope must have a force of 10084,21 N

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