11. A lorry accelerates from rest at a constant rate 'a' covering some distance and then decelerates at a constant
rate B' to come to rest again. If the total distance covered by the lorry is s, then
(a) find the maximum velocity attained by the lorry.
(b) total time taken by the lorry to cover the distance s.
Answers
Answered by
0
Answer:
A
Explanation:
Lets consider, v= maximum velocity,
When A car accelerates from rest at a constant rate α
From 1st equation of motion,
v=u+at
v=0+αt
1
v=αt
1
t
1
=
α
v
After car decelerate at the rate β,
From 1st equation of motion,
v=u+at
0=v−βt
2
v=βt
2
t
2
=
β
v
Total time elapsed,
t=t
1
+t
2
t=
α
v
+
β
v
t=v(
αβ
α+β
)
v=(
α+β
αβ
)t
From the above figure,
The total distance covered is equal to the area under the velocity-time graph
S=
2
1
×v×t
s=
2
1
(
α+β
αβ
)t
2
The correct option is A
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