39question 1:
let the two points be A and B.
now let velocity at A be `u`
vel at B= 45
using v=u+at , we have 45=u+6a ---(1)
using v2-u2=2as , we have
452-u2=2.a.180 ---(2)
so u have 2 equations in 2 unknowns `u` and `a`.
solve to get` u` and `a`
I know these are simple but it's not striking me...
Q1- A car moving with constant acceleration covers the distance between two points 180m apart in 6 sec.its speed as it passes the second point is 45m/s.What is its acceleration and its speed at the first point ? Explain How please
Q2 - A car moving with a speed of 50km/hr can be stopped by brakes after atleast 6m.If the same car is moving at a speed of 100km/hr the minimum stopping distance is ?Explain please
Thanks
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15 Answers
12...
v2-u2=2as
here v=0
u= 50km/h
s= 6 m=0.006km
so
0-50.50=2a.0.006
so a==2500/0.012
now....
v2-u2=2as
and u=100 here
0-100.100=-2*2500/0.006*s
so s=0.012
s=12m
i guess
im not sure
3911.
now.......v=45......s=180m....t=6s
v2-u2=2as
45*45-u2=2a.180................(1)
and also
v=u+at
45=u+6a
subs this in 1 equaton
(u+6a)2-u2=360a
u2+36a2+12ua-u2=360a
36a2+12ua=360a
36a+12u=360
u+3a=30
u+6a=45
3a=15
a=5m/s2
and u+15=30
u=15m/s..........
1hehe b555.......shud i pink urs also............urs isnt complete though hehehehehehehe
3The answer for the second one is 24m but i don't know how to get it.
39tormented i havent really put it on a pepr but what akand has done seems to be correct.
1i dont even hav a pen near me.............i was just typing.....so cud hav made sum mistake........
1but will d retardation in both cases be same????? it has to be na......same car......
3Yeah i don't think there is any fault in that but the book says 24m.By the way this question was a previous AIEEE question.
1well if u find d correct method post it here.....hehe........
all d best to u tormented.........
its been more than two months since i solved a question ...and i did it today hehehehe
3Okay i guess i got it !
s1 = 6 s2 = x
we know that s=u2 / 2a and here 1/2 and a are constants so
s is proportional to u2
s1 / s2 = (u1)2/(u2)2
Solve and we get 24m !