Question

A 3.5 kg object moving at 8.1 m/s in the positive direction of an x axis has a one-dimensional elastic collision with an object of mass M, initially at rest. After the collision the object of mass M has a velocity of 5.2 m/s in the positive direction of the x axis. What is mass M?

Answer 1

So the mass of the second object M will be 1.951 kg

Step-by-step explanation:

We have given mass of the first object
`m_1=3.5kg` and its velocity
`v_1=8.1m/sec`

Mass of the second object
`m_2=M` it is at rest so its velocity
`v_2=0`

From conservation of momentum we know that

Initial momentum = final momentum

So
`m_1v_1+m_2v_2=(m_1+m_2)v`

`3.5* 8.1+M* 0=(3.5+M)5.2`

`28.35=18.2+5.2M`

M = 1.951 kg