12. In a car race, car A takes 2 s less than car B and
passes the finishing point with a velocity v more
than the velocity with which car B passes the point.
Both the cars start from rest and travel with constant
accelerations of aA = 3 m/s² and aB = 2 m/s². The value of v is _
Answers
Answer:
Explanation:
Consider that A takes t 1 second, then according to the given problem, B will take (t 1 +t) seconds. Further let v 1 be the velocity of B at finishing point, then velocity of A will be (v1 +v). Writing equations of motion for A and B.
v 1 +v=a 1 t 1 equation 1
v 1 =a 2 (t 2 +t) equation 2
From equations (1) and (2 ), we get
v=(a 1 −a 2 )t 1 −a 2 t equation 3
Total distance travelled by both the cars is equal
S A =S B
⇒ 1/2 a 1 t 1 ^(2) = 1/2 a 2 (t 1 +t) ^(2)
⇒t 1 = [root(a2) x t] / [root (a1) - root (a2)]
Substituting this value of t 1 in equation (3), we get
v=[root ( a 1 a 2 )] x t
By this formula,
v = [root ( 3 x 2 ) ] x 2
v= 2 x (root 6 )
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