# NCERT Question 11 - Chapter 9 Class 9 - Force and Laws Of Motion

Last updated at May 24, 2019 by Teachoo

Last updated at May 24, 2019 by Teachoo

Transcript

NCERT Question 11 Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m sโ1 before the collision during which they stick together. What will be the velocity of the combined object after collision? Mass of object 1 = ๐_1 = 1.5 kg Mass of object 2 = ๐_2 = 1.5 kg Velocity of object 1 = u1 = 2.5 m/s Velocity of object 2 = u2 = โ 2.5 m/s Note: u2 is negative since it is in opposite direction of u1 After collision, the objects stick together โด Combined mass = m1 + m2 = 1.5 + 1.5 = 3 kg Velocity of combined object = v Finding momentum before and after collision Momentum before Momentum = Momentum of Object 1 + Momentum of Object 2 = 1.5 ร 2.5 + 1.5 ร (โ2.5) = 1.5 ร 2.5 โ 1.5 ร 2.5 = 0 Momentum after Momentum = Total Mass ร Velocity After = 3 ร v = 3v Momentum after Momentum = Total Mass ร Velocity After = 3 ร v = 3v According to law of conservation of momentum, Total momentum before collision = Total momentum after collision 0 = 3v v = 0/3 v = 0 m/s

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Class 9

Chapter 9 Class 9 - Force and Laws Of Motion

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.