Answer:
The initial speed of the linebacker just before the collision was 4.6 m/s.
Step-by-step explanation:
Mass of OSU linebacker, m = 110 kg
Mass of UM quarterback, m' = 85 kg
Just after they collide, they are momentarily stuck together, the common speed is, V = 2.6 m/s
Initial speed of quarterback is 0 as it was at rest initially, u' = 0
Let u was the initial speed of the linebacker just before the collision. As they struck together, the momentum remains conserved. So,

So, the initial speed of the linebacker just before the collision was 4.6 m/s.