Question

A 43.3 kg girl is standing on a 125 kg plank.
The plank, originally at rest, is free to slide on
a frozen lake, which is a flat, frictionless sup-
porting surface. The girl begins to walk along
the plank at a constant speed of 1.87 m/s to
the right relative to the plank.
What is her velocity relative to the ice sur-
face?
Answer in units of m/s



What is the velocity of the plank relative to
the ice surface?
Answer in units of m/s