Question

A hockey puck of mass m traveling along the x axis at 4.5 m/s hits another identical hockey puck at rest. If after the collision the second puck travels at a speed of 3.5 m/s at an angle of 30° above the x axis, what is the final velocity of the first puck?

Answer 1

The value of final velocity of the first hockey puck
`v_(1) _(f) =` 2.3
`(m)/(s)`

Step-by-step explanation:

Mass of hockey puck = m

Initial velocity
`v_(1)_(i) = 4.5 (m)/(s)`

From conservation of momentum principal

4.5 m = m
`v_(1x) _(f)` + m ×
`\cos 30` × 3.5

`v_(1x) _(f)` = 1.5
`(m)/(s)`

0 = m
`v_(1y) _(f)` + m ×
`\sin 30` × 3.5

`v_(1y) _(f)` = - 1.75
`(m)/(s)`

Now final velocity of first puck

`v_(1) _(f) = \sqrt{v_(1x) _(f)^(2) + {v_(1y) _(f)^(2) }`

Put the values in above formula we get

`v_(1) _(f) = \sqrt{(1.5)^(2) + (-1.75)^(2) }`

`v_(1) _(f) =` 2.3
`(m)/(s)`

This is the value of final velocity of the first hockey puck.