The weight of a 1420 kg car is supported equally by its four tires, each inflated to a gauge pressure of 35 psi. (a) Determine the area of contact each tire makes with the road. (b) If the gauge pressure in the tires is increased, does the area of contact increase, decrease, or stay the same. (c) Calculate the necessary gauge pressure in the tires to give an area of contact of 116 cm2 for each tire.

Respuesta :

Answer:

a.  [tex]Area=144cm^{2}[/tex]

b. decrease

c. 43.5psi

Explanation:

Answer:

a.  [tex]Area=144cm^{2}[/tex]

Explanation:

from the questions, the car has four tires which support the weight equally.we can conclude that the weight support by each tire is

weight support of each tire =1420/4=355kg.

a. since [tex]pressure=\frac{force}{area}[/tex]

we need to determine the force, [tex]F=mg\\[/tex]

the "g" is the acceleration due to gravity which has a constant value of [tex]9.8m/s^{2}[/tex]

hence the force on each tire is

[tex]F=mg\\F=355*9.8\\F=3479N\\[/tex]

Also, since the pressure is giving in psi, we have to convert it to pascal

since 1psi=6895pascal

hence 35psi to pascal is

[tex]35*6895\\241325pa[/tex].

From the expression for pressure

[tex]pressure =\frac{force}{area}\\[/tex]

we have

[tex]Area=\frac{force}{area}\\\\ Area=\frac{3479}{241325} \\Arae=0.0144\\[/tex]

to cm[tex]^{2}[/tex] we multiply by [tex]10^{4}[/tex]

[tex]Area=144cm^{2}[/tex]

b. The effect of the pressure can be determine from the relationship between the pressure and the area using the pressure formula

[tex]p=\frac{force}{area} \\p\alpha \frac{1}{A}\\[/tex]

hence an increase in the pressure will lead to a decrease in  the contact Area

C. if the area ia now [tex]116cm^{2} \\[/tex] converting to meter square

[tex]116/10^{4} \\Area=0.0116m^{2} \\[/tex]

the pressure now is

[tex]pressure=\frac{force}{area} \\Pressur=\frac{3479}{0.0116}\\ pressure=299913.8pa\\[/tex]

converting to psi we have

[tex]299913.8/6895\\pressure=43.5psi[/tex]

(a) The area of contact of each tire is 114.17 cm².

(b) If the gauge pressure increases, the contact area decreases.

(c) The necessary gauge pressure in the tires is 43.5 psi.

Area of contact of each tire

The area of contact of each tire is calculated as follows;

P = F/A

A = F/P

where;

  • A is the area of contact
  • F is the applied force
  • P is the pressure

Weight of each tire, W = mg/4 = (1420 x 9.8)/4 = 3479 N

Pressure of each tire = 35 psi = 241,317 Pa

A = W/P

A = 3479/241317

A = 0.014417 m²

A = 144.17 cm²

If the gauge pressure increases, the contact area decreases.

Gauge pressure of each tire

When the contact area is 116 cm² = 0.0116 m², the gauge pressure of each tire is calculated as follows;

P = W/A

P = 3479/0.0116

P = 299,913.8 Pa

convert to psi by dividing with 6895

P = 43.5 psi

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