Question

Two hockey players skating on essentially frictionless ice collide head-on. Madeleine, of mass 65.0 kg, is moving at 6.00 m/s to the east just before the collision and at 3.00 m/s to the west just after the collision. Buffy, of mass 55.0 kg, is moving at 3.50 m/s to the east just after the collision. Find Buffy's velocity (magnitude and direction) just before the collision.

Answer 1

Step-by-step explanation:

It is given that,

Mass of Madeleine,
`m_1=65\ kg`

Initial speed of Madeleine,
`u_1=6\ m/s` (due east)

Final speed of Madeleine,
`v_1=-3\ m/s` (due west)

Mass of Buffy,
`m_2=55\ kg`

Final speed of Buffy,
`v_2=3.5\ m/s` (due east)

Let
`u_1` is the Buffy's velocity just before the collision. Using the conservation of linear momentum as :

`m_1u_1+m_2u_2=m_1v_1+m_2v_2`

`65* 6+55* u_2=65* (-3)+55* 3.5`

`u_2=-7.13\ m/s`

So, the initial speed of the Buffy just before the collision is 7.13 m/s and it is moving due west. Hence, this is the required solution.