A person has a reasonable chance of surviving a car crash if the deceleration is no more than 30 'g's (g=9.8m/s2). Calculate the force on a 70 kg person undergoing this acceleration. What distance is travelled if the person is brought to rest at this rate from 100 km/h?​

Respuesta :

Thus, the distance traveled by automobile is [tex]=1.31m[/tex]

How do you find the distance traveled by automobile?

  • Newton's second law can be used to compute the force being applied to the subject.
  • The force is calculated as the product of the vehicle's acceleration and the person's mass.
  • Newton's third law can be used to calculate the distance driven by a car.

The mass of the person is [tex]m=65kg[/tex]

The deceleration of the automobile is [tex]a=30g[/tex]

The acceleration due to gravity is [tex]g=9.81m/s.[/tex]

The initial velocity of the automobile is [tex]v_{i}=100 km/h*\frac{1m/s}{3.6km/h} =27.78m/s[/tex]

Determination of the force exerted on the person:

The force applied to the person can be calculated using Newton's second law as follows:

[tex]F=ma[/tex]

[tex]30g[/tex]Here, m denotes the person's mass, while a denotes the car's acceleration. Because the driver is moving at 30g, the car's acceleration is assumed to be positive.

Substitute the values as 70 kg for [tex]m,(30g)[/tex] for a, and[tex]9.81m/s^{2}[/tex]

for g in the above equation.

[tex]F=70kg*30g[/tex]

   [tex]=70kg*30g*9.81m/s^{2} (\frac{1N}{1kg*m/s^{2} })[/tex]

   [tex]=20,601N[/tex]

Thus, the force acting on the person is [tex]=20,601N[/tex]

Determination of the distance traveled by automobile:

The final velocity of the car can be calculated using Newton's third law and represented as follows:

[tex]v_{f} ^{2}=v_{i} ^{2}+2ad[/tex]

[tex]d=\frac{v_{f} ^{2}=v_{i} ^{2}}{2a}[/tex]

Here [tex]v_{f}[/tex] is the final velocity of the automobile. The final velocity of the automobile becomes 0 m/s as the automobile comes to rest. The acceleration is taken to be negative because the automobile is decelerating at [tex]30g[/tex]

Substitute the values as [tex]0 m/s[/tex] for[tex]v_{f} =27.78m/s[/tex], for[tex]v_{i} ,(-30g)[/tex],  for a, and  [tex]9.81m/s^{2}[/tex]for g in the above equation.

[tex]d=\frac{(0 m/s)^{2} - (27.78m/s)^{2} }{2*(-30)*9.81m/s^{2} }[/tex]

[tex]=1.31m[/tex]

Thus, the distance traveled by automobile is[tex]=1.31m[/tex]

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