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spayn [35]
3 years ago
10

A 73-kg person in a moving car stops during a car collision in a distance of 0.80 m . The stopping force that the air bag exerts

on the person is 8000 N. Determine the speed of the person before the air bag opens up.
Physics
2 answers:
Vlad [161]3 years ago
6 0

Answer:

13.24m/s

Explanation:

To solve this exercise we go back to the kinematic equations of motion in search of acceleration and the initial speed at which the object was moving.

Once found it will be possible to determine the estimated time.

Our values are:

F=-8000N

m=73Kg

Applying the Second Newton's Law:

a= \frac{F}{m}

a=\frac{8000}{73}

a = 109.58m/s^2

During the collision the distance is 0.8m and there is not final velocity, then

v_f^2 = v^2_0+2ax

0 = v^2_0+2(109.58)(0.8)

v_^2_0 = 175.328

v_0 = 13.24m/s

From the Kinetic Equation we have also

v_f = v_0 - at

0 = 13.24-(109.58)t

t= 0.1208s

Therefore the velocity before the air bag opens up is 13.24m/s in an interval time of 0.12s to open the air bag

fredd [130]3 years ago
3 0

Answer:

 v₀ = 13.24 m / s

Explanation:

Let's use Newton's second law to find the average acceleration during the crash

       F = m a

.       a = F / m

       a = 8000/73

       a = 109.59 m / s²

Now we can use the kinematic equations to find the initial velocity, since when the velocity stops it is zero (v = 0)

       v² = v₀² - 2 a x

       v₀² = 2 a x

       v₀ = √  2 a x

       v₀ = √ (2 109.59 0.80)

       v₀ = 13.24 m / s

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v² = u² + 2as where u = initial speed of driver = 50 mi/h = 50 × 1609 m/3600 s = 22.35 m/s, v = final speed of driver = 30 mi/h = 30 × 1609 m/3600 s = 13.41 m/s, a = deceleration of driver and s = distance moved by driver = 385 ft = 385 × 0.3048 m = 117.35 m

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a = v² - u²/2s

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