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in coming to a stop, a car leaves skid marks 65m long on a highway.assuming a deceleration of 4m/s^2,estimate the speed of the car just before breaking?

Respuesta :

btsangiie13280

Assuming a CONSTANT deceleration of 7.00 m/s^2,
final velocity, v = 0 m/s
acceleration, a = -7.00 m/s^2,
displacement, s = 92 m

using v^2 = u^2 + 2as
0^2 = u^2 + 2 (-7.00) (92)
initial velocity, u = sqrt (1288) = 35.9 m/s

This is the speed of the car just before braking.
i dont take credit for this answer i just simply did my research so you can get your answer quickly! hope this helped <3
carlosego

By definition, we have that the final speed is given by:

[tex] vf ^ 2 = vo ^ 2 + 2ad
[/tex]

Where,

vo: initial speed

a: acceleration

d: displacement

Substituting values we have:

[tex] 0 ^ 2 = vo ^ 2 + 2 (-4) (65)
[/tex]

From here, we clear the value of the initial velocity.

We have then:

[tex] 0 = vo ^ 2 - 520

vo ^ 2 = 520
[/tex]

[tex] vo = \sqrt{520} [/tex]

[tex] vo = 22.8 \frac{m}{s}
[/tex]

Answer:

The speed of the car just before breaking was:

[tex] vo = 22.8 \frac{m}{s} [/tex]

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