A 30-kg girl on friction-free roller blades pushes away a 25-kg boy also on roller blades at 1 m/s. The girl's speed is
A) 0.45 m/s.
B) 0.55 m/s.
C) 0.83 m/s.
D) 1.2 m/s.
Question 2
A 200-g hockey puck is launched up a ramp that is inclined at a 30 angle above the horizontal.
The coefficients of static and kinetic friction between the puck and the ramp are s = 0.40 and k = 0.30, respectively, and the puck's initial velocity at the base is 3.8 m/s parallel to the sloping surface of the ramp. What speed does the puck have when it slides back down to its starting point?
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