For Question 6:
The formula for momentum to express the conservation of momentum of two objects in a collision is:
m1 • v1 + m2 • v2 = m1 • v1' + m2 • v2'
m1 and m2 are the masses so
63v1 + 55v2 = 63v1' + 55v2'
v1 and v2 represent the velocities before the collision, so
(63)(0) + (55)(0) = 63v1' + 55v2'
v1' and v2' represent the velocities after the collision, so
(63)(0) + (55)(0) = (63)(3.3) + (55)v2' <-- We're looking for v2'
0 + 0 = 207.9 + 55v2'
-207.9 = 55v2'
-3.78 m/s = v2'
The answer is negative because the 55kg skater is moving to the left.
For Question 7:
The formula for momentum is p = m • v
so we have:
3.9 = .15v
26 m/s = v