A 3.0 kg object moving 8.0 m/s in the positive x-direction has a one-dimensional elastic collision with an object of mass, M, initially at rest. After the collision the object of unknown mass has a velocity of 6.0 m/s in the positive x direction. What is M

Explanation:

According to law of conservation of momentum

m1u1+ m2u2 = (m1+m2)v

m1 and m2 are the masses of the object

u1 and u2 are their initial velocities

v is their common velocity

Given

m1 = 3kg

m2 = M

u1 = 8m/s

u2 = 0m/s (object at rest)

v = 6.0m/s

Substitute and get M

3(8) + M(0) = (3+M)6

24 = 18+6M

24-18 = 6M

6 = 6M

M = 1kg

Hence the mass M is 1kg

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