Answer:
The two skaters will move with a common speed of 1.19 m/s.
Explanation:
Given that,
Mass of Alex, 
Initial velocity of Alex, 
Mass of Barbara, 
Initial velocity of Barbara, 
After the collision, the two skaters move together at a common velocity. Let V is the common velocity. Using the conservation of momentum as :

Magnitude of final velocity:

So, the two skaters will move with a common speed of 1.19 m/s.
E = mc²
E = 0.235 kg · (3×10⁸ m/s)² = 0.235 · 9×10¹⁶ kg·m/s²
E = 2.115×10¹⁶ J
The answer is d) 2.12×10¹⁶ J
Answer:
part a: 4.25s
part b: 180.625m
Explanation:
part a:
what we know: vi=42.5m/s
t=?
vf=0
g= -10m/s^2
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equation: vf-vi/g=t
plug in: -42.5m/s/ - 10m/s^2 = 4.25s
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part b: 42.5m/s x(times) 4.25s = 180.625m