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Engineering
4 months ago

three balls A,B and C of masses 2kg, 4kg and 8 kg

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Three balls A, B and Cofmasses 2 kg,4kg and 8 kgrespectivelymove along the same straight line and in the same direction, with velocities 4 m/s, 1 m/s and 3/4 m/sec. If A collides with B and subsequently B collides with C. Find the velocity of ball A and ball B after collision, taking the coefficient of restitution as unity.

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S safeer
Answered 4 months ago

case 1 

consider the collision of A and B. Let v and v' be the velocities after collision

by momentum conservation

2v+4v'=12 or v+v'=6...............(1)

relative velocity after impact = -e (relative velocity before impact)

v-v'=-1(4-1) or v-v' =-3 ...................(2)

solving (1) and (2) 

v'=3 m/s and v= 0

hence after collision A is at rest and B moves with 3m/sec

now consider the collision of  B and C

let v and v' be the new velocities after collision in this case.

from momentum conservation and applying the condition 

relative velocity after impact = -e (relative velocity before impact)

let v and v' be the new velocities after collision in this case

we can find that 

v=0 and v'=9/4

there for VA=VB=0

S safeer
Answered 4 months ago
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