On a foggy day, two drivers spot in front of each other when 80 meter apart. They were traveling at 70kmph and 60kmph. Both apply brakes simultaneously which retard the cars at the rate of 5 [m/s²]. Which of the following statements is correct?
a) The collision will be averted
b) The collision will take place
c) They will cross each other
d) They will just collide.

Find the distance it takes each to stop. Given initial velocity and acceleration, do you know which equation of motion involves distance?

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Originally Posted by ebaines

Find the distance it takes each to stop. Given initial velocity and acceleration, do you know which equation of motion involves distance?

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Yes Ebaines..
s= ut + 1/2 at²
and, v²- u²= 2as
s= distance

Quote:

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Originally Posted by Bebo_momo

Yes Ebaines..
and, v²- u²= 2as

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Good - so what do you get as values for s for the two cars?

Actually I don't know whether the given velocities are 'v' or 'u'??

37.6 m for first one and 27.5 m for the second one?? Is it so??
:( See, I am very weak in Kinematics. If I am wrong then don't make a fun of me...

Close - I get 37.8m and 27.8m.

In the equation v^2-u^2 = 2as, v is the starting velocity and u= ending velocity of an object So in this case v is 70 KPH for one car and 60 KPH for the other, and u is 0 for both. I prefer writing the equation as:



where is initial velocity and is final velocity, but you should use whatever terms your book uses.

Thanks Ebaines! :)