Question

• A car moves with a uniform acceleration
along a straight line ABC. At A its speed
is 5 ms-1 and at C its speed is 25 ms-l. If
AB:BC is 1:2, then the ratio of the times
taken by the car to cover distances AB and
BC respectively is
a) 1:1
b) 1:2
c) 2:5
d) 3:8
​

Answer 1

Answer:

1:2

Explanation:

let the distance be x and 2x.

so,AB=x and BC=2x

AC=x+2x=3x

let the time taken to travel AB and AC be t1 and t2 respectively..

x=5t1+1/2a(t1)²

=>3x=15t1+3/2a(t1)² ....equ(i)

[multiplying throughout by 3]

and

3x=5t2+1/2a(t2)² ....equ(ii)

on subtracting them ,[equ(i)-equ(ii),]

0=15t1-5t2+a/2{3t1²-t2²}

0=5(3t1-t2)+a/2(3t1+t2)(3t1-t2)

0=(3t1-t2) {5+a/2(3t1+t2)}

(as 2nd term≠0)

so,t1:t2=1:3

so,t1:t2=1:3t2:t1=3:1

so,t1:t2=1:3t2:t1=3:1(t2-t1)/t1=2/1

so,t1:t2=1:3t2:t1=3:1(t2-t1)/t1=2/1t1:(t2-t1)=1/2

so,the ratio of the time taken to cover AB and BC is 1:2...

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Answer 2

Answer:

here is your answer

Explanation:

answer is

b) 1:2