(adsbygoogle = window.adsbygoogle || []).push({}); drag and time to slow down... and apparent weight. -__-

A 1.58 m wide, 1.44 m high, 1300 kg car hits a very slick patch of ice while going 20.0 m/s. Air resistance is not negligible.

If friction is neglected, how long will it take until the car's speed drops to 18.0 m/s?

Ok drag is equal to = 1/4 * A * v^2

v^2 = 400 and A = 1.44*1.58

I divided this drag by the mass to get acceleration in the x direction and then used this equation:

[tex]v_f = v_i + a t[/tex]

t here is delta t...

final velocity is what I want = 18 and initial is 20 while acceleration is the one I got from analyzing the drag force....

I get 11.4 seconds and it's wrong.

I did it again and again to make sure there are no errors but nothing changed.

[EDIT]

btw does anybody know how to get the mass from a chart of apparent weight vs time? I know it's w/g but I only have apparent weight and not weight... I can't tell when it's equal to the real weight. (when a = 0 but I can't tell from the chart).

Here's the chart:

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# Homework Help: Drag and time to slow down -__-

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