For 50 km/h skids 15m with brake
v^2 = u^2 - 2as
0 = (50x10^3 / 3600)^2 - 2a(15)
(50x10^3 / 3600)^2 = 2a(15) ---(1)
For 150 km/h,
v^2 = u^2 - 2as
0 = (150x10^3 / 3600)^2 - 2as
(150x10^3 / 3600)^2 = 2as ---(2)
(2)/(1)
(150 / 50)^2 = s/15
s = 135 m
2007-03-01 03:15:16
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answer #1
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answered by seah 7
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The initial velocity is 50 km/h and the final velocity is 0. So, let us use the equation, v^2 - u^2 = 2 a.s where s is the acceleration and s is the distance travelled.
Here we have 0 - 50 X 50 = 2. -a . 15 ( we use - sign before a to denote deceleration). The negative sign gets cancelled out.
50 X 50 = 30 a or a = 2500 / 30 = 250/3
Now let us calculate the second equation:
0 - 150 X 150 = 2. 250 .-s / 3
Again ignoring the negative sign on both sides,
150 X 150 = 500s/3
s = 3.150.150/500 = 3.3.50.150/500 (we just expressed 150 as 3.50 for simplification)
= 9.150/10 = 9.15 = 135 m
Please note that we have not used a calculator anywhere in the above solution.
2007-03-01 03:41:30
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answer #2
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answered by Swamy 7
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here, in this concern, the conception must be that the frictional tension continues to be an analogous and so the deceleration produced additionally to be an analogous. by equations of action, v^2 = u^2 + 2as (notice that ingredient is absent in this equation and that too time isn't given interior the priority) because of the fact the case is with deceleration, ie destructive acceleration and intensely final speed v =0 because of the fact the vehicle is composed of relax, the expression will become 2as = u^2 consequently the relation between s and u is: s is immediately proportional to the sq. of the fee. subsequently, s2/s1 = (u2/u1)^2 advice: Which one to be discovered would desire to be interior the left side numerator. here s2 the skidding distance is needed. particularly straightforward manipulation. So s2 = s1*(u2/u1)^2 it particularly is how we would desire to grant the attitude particularly collectively as writing any front examination attending purpose style questions. Now plugging the given values and simplifying we get, s2 =15 * (a hundred and fifty/50)^2 = 15 * 9 = one hundred thirty five m
2016-12-18 03:16:03
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answer #3
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answered by ? 4
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If it is a straight linear equation then-:
150 / 50 = 3
3 x 15 = 45 metres
2007-03-01 03:08:16
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answer #4
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answered by Doctor Q 6
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Since we expect that their deceleration rates to be equal, we can use ratio and proportion.
Since a = v^2/(2d), then
v1^2/(2d1) = v2^2/(2d2)
50^2/(2*15) = 150^2/(2*x)
x = (150^2/50^2)*15
x = 135 m.
2007-03-01 03:09:41
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answer #5
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answered by Moja1981 5
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