Answer:
(a) the velocity of the plank relative to the frozen pond is 0.825 m/s
(b) the velocity of the plank relative to the frozen pond is 0.275 m/s
Explanation:
Given information:
student's mass, = 50kg
wooden plank's mass, = 150 kg
Note : all the velocity is in vector
student's velocity relative to the plank, = 1.10i m/s
student's velocity relative to frozen pond,
= +
(a) the velocity of the plank relative to the frozen pond,
to calculate the velocity of the plank relative to the frozen pond, we can start from the momentum, p.
The total momentum is
p = +
is the velocity of student relative to the frozen pond
is the velocity of the plank relative to the frozen pond
at rest on a frozen pond, the momentum is 0. so,
p = 0
+ = 0
= -
*the negative indicates that the student and the plank are moving in opposite direction
now subtitute student's velocity relative to frozen pond, to the equation.
= -
= -
- ) = -
- = -
= -
= -
= -0.825 i m/s
the velocity of the plank relative to the frozen pond is 0.825 m/s in the opposite direction
(b) the velocity of the student relative to the frozen pond
= +
= (1.10i m/s) + (- 0.825i m/s)
= (1.10i m/s - 0.825i m/s)
= 0.275i m/s
the velocity of the plank relative to the frozen pond is 0.275 m/s.