Question

A body of mass 4.0 kg makes an elastic collision with another body at rest and...

A body of mass 4.0 kg makes an elastic collision with another body at rest and continues to move in the original direction but with 1/7 of its original speed. (a) What is the mass of the other body? (b) What is the speed of the two-body center of mass if the initial speed of the 4.0 kg body was 6.3 m/s?

Homework Answers

Answer #1

given :

mass of first body = m1 = 4 kg

mass of second body = m2 = ?

initial speed of m1 = u

final speed of m1 = u/7.

a) from conservation of linear momentum :

--------(i)   [v = final speed of m2, initial speed of m1 = 0]

as the collision is elastic, e = 1, therefore ,

-----(ii)

from equation (ii) :

putting the value of v in equation (i)

[answer]

b) initial speed of m1 = u = 6.3 m/s.

speed of centre of mass of the two bodies = [answer]

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