- #1
ngorecki
- 37
- 0
conservation of momentum??
A 45.0 kg girl is standing on a 156 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.51 m/s relative to the plank.
(a) What is her velocity relative to the ice surface?
(b) What is the velocity of the plank relative to the ice surface?
variable:
girl=45kg
plank=156kg
Vi=0m/s
Vf=1.51m/s
mavai + mbvbi = mavaf +mbvbf
since Vi=0m/s left side of consercation of momentum equation =0
0 = 45(Vf) + 156(1.51)
0 = 45(Vf) + 235.56
-235.56 = 45(Vf)
-5.23 = Vf
this answer is not possible because the absolute value of part a and b should add up to 1.51 while 5.23 is already much bigger
Homework Statement
A 45.0 kg girl is standing on a 156 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.51 m/s relative to the plank.
(a) What is her velocity relative to the ice surface?
(b) What is the velocity of the plank relative to the ice surface?
variable:
girl=45kg
plank=156kg
Vi=0m/s
Vf=1.51m/s
Homework Equations
mavai + mbvbi = mavaf +mbvbf
The Attempt at a Solution
since Vi=0m/s left side of consercation of momentum equation =0
0 = 45(Vf) + 156(1.51)
0 = 45(Vf) + 235.56
-235.56 = 45(Vf)
-5.23 = Vf
this answer is not possible because the absolute value of part a and b should add up to 1.51 while 5.23 is already much bigger