If the car’s speed decreases at a constant rate from 71 mi/h to 50 mi/h in 3.0 s, what is the magnitude of its acceleration, assuming that it continues to move in a straight line? What distance does the car travel during the braking period?

Respuesta :

Answer:

The acceleration and the distance are 25200 mi/h² and 0.1008 mi.

Explanation:

Given that,

Initial speed = 71 mi/h

Final speed = 50 mi/h

Time = 3.0 s

(a). We need to calculate the acceleration

Using equation of motion

[tex]v=u+at[/tex]

[tex]a=\dfrac{v-u}{t}[/tex]

Put the value in the equation

[tex]a=\dfrac{(50-71)\times3600}{3}[/tex]

[tex]a=-25200\ mi/h^2[/tex]

Negative sign shows the deceleration.

(b). We need to calculate the distance

Using equation of motion

[tex]v^2=u^2+2as[/tex]

[tex](50)^2=(71)^2+2\times(-25200)\times s[/tex]

[tex]s=\dfrac{(50)^2-(71)^2}{-25200}[/tex]

[tex]s=0.1008\ mi[/tex]

Hence, The acceleration and the distance are 25200 mi/h² and 0.1008 mi.

The distance traveled by the car when the car is constantly deaccelerating at a rate of 25200 miles/h² is 0.0504 miles.

Given to us

Initial Velocity of the car, u = 71 miles/h

Final Velocity of the car, v = 50 miles/h

Time = 3.0 s  [tex]=\dfrac{3}{3600}[/tex] hour

What is the acceleration of the car?

According to the first equation of motion, acceleration can be written as,

[tex]a=\dfrac{v-u}{t}[/tex]

substituting the values we get,

[tex]a=\dfrac{50-71}{\dfrac{3}{3600}}[/tex]

[tex]a=-25,200\rm\ miles/h^2[/tex]

Thus, the acceleration of the car is -25,200 miles/h².

What distance does the car travel during the braking period?

According to the third equation of motion,

[tex]v^2-u^2=2as[/tex]

Substituting the values we get,

[tex](50)^2-(71)^2=2(-25200)s[/tex]

[tex]s = 0.0504 \rm\ miles[/tex]

Thus, the distance car travel during the braking period is 0.0504 miles.

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