Answer:
a)
b) º
c)
Explanation:
From the exercise we know that the collision between Daniel and Rebecca is elastic which means they do not stick together
So, If we analyze the collision we got
To simplify the problem, lets name D for Daniel and R for Rebecca
a)
Since Daniel's initial velocity is 0
Now, lets analyze the movement in the vertical direction
Since
Now, we can find the magnitude of Daniel's velocity after de collision
b) To know whats the direction of Daniel's velocity we need to solve the arctan of the angle
º
c) The change in the total kinetic energy is:
ΔK=
ΔK=
That means that the kinetic energy decreases