A mechanic pushes a 2.20 ✕ 103-kg car from rest to a speed of v, doing 5,280 J of work in the process. During this time, the car moves 23.0 m. Neglecting friction between car and road, find v and the horizontal force exerted on the car.

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Answer:

The velocity of car is 2.19 [tex]\frac{m}{s}[/tex] and horizontal force exerted on the car is 229.5 N

Explanation:

Given :

Mass of car [tex]m = 2.20 \times 10^{3}[/tex] Kg

Work done by car [tex]W = 5280[/tex] J

Displacement [tex]d = 23[/tex] m

From work energy theorem,

 [tex]W = \Delta K[/tex]

But here final velocity is zero so we write,

 [tex]W = \frac{1}{2} mv^{2}[/tex]

Find velocity,

   [tex]v = \sqrt{\frac{2W}{m} }[/tex]

   [tex]v = \sqrt{\frac{2 \times 5280}{2200} }[/tex]

   [tex]v = 2.19[/tex] [tex]\frac{m}{s}[/tex]

Now, horizontal force exerted on the car,

  [tex]W = F \times d \cos \theta[/tex]

   [tex]F = \frac{W}{d}[/tex]                     (∵ [tex]\cos \theta = 1[/tex] )

   [tex]F = \frac{5280}{23}[/tex]

   [tex]F = 229.5[/tex] N

Therefore, the horizontal force exerted on the car 229.5 N

The speed of the car "v" is 2.19m/s

The horizontal force exerted on the car is 229.57N

The work done on the car is equal to the kinetic energy as shown:

W = KE

Since kinetic energy is expressed as [tex]KE=\frac{1}{2}mv^2\\[/tex]

[tex]W=0.5mv^2\\v^2=\frac{W}{0.5m}\\v^2=\frac{5280}{0.5(2200)}\\v^2=\frac{5280}{1100}\\v^2= 4.8\\v=\sqrt{4.8}\\v= 2.19m/s[/tex]

Hence the speed of the car "v" is 2.19m/s

The horizontal force exerted on the car is expressed as;

[tex]W=Fd\\F =\frac{W}{d}\\F=\frac{5280}{23}\\F= 229.57N[/tex]

Hence the horizontal force exerted on the car is 229.57N

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