Vyky
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Vyky asked in Education & ReferenceHomework Help · 1 decade ago

Last question and I dont understand it :( physics help?

A driver a car traveling at 15.0 m/s applies the brakes, causing a uniform acceleration of -2.0 m/s^2. how long does it take the car to accelerate to a final speed of 10.0 m/s? How far has the car moved during the braking period?

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  • 1 decade ago
    Favorite Answer

    use eqn

    vf=vi+at

    t=(vf-vi)/a

    t=(10-15)/(-2)

    t=2.5 s

    since you know time you can use eqns

    d=0.5(vi+vf)t

    d=vit+0.5at^2

    but ill just use an eqn that doesnt use time

    vf^2=vi^2+2ad

    d=(vf^2-vi^2)/ 2a

    d= [(10^2)-(15^2)]/ 2(-2)

    d=31.25

  • 1 decade ago

    vf^2-vo^2=2ax

    10^2-15^2=2(-2)x

    100-225=-4x

    -125=-4x

    31.25 m=x

    vf=vo+at

    10=15+-2)t

    -5=-2t

    2.5 s=t

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