Iunderstand it, but i got confused on the part where it says that they move as one mass or get stuck together

4. Before the dog jumps out, initial momentum=0

After the dog jumps out, final momentum=initial momentum=0

So dog's momentum+canoe's momentum=0

Dog's momentum=mass*velocity

=15*1.2

=18

Canoe's momentum= -(dog's momentum)= -18

Canoe's velocity=-18/40=-0.45m/s

The - sign means the direction is opposity to the dog's jump.

5. Assume the Pennridge player's direction is +ve

Initial momentum before collision=Pennridge player's momentum + Souderton player's momentum

=80*3+70*(-2.5)

=240-175

=65

As they are stuck together after collision, the final mass=80+70=150

Final momentum=Initial momentum=65

Final velocity=Final momentum/Final Mass

=65/150

=0.4333m/s in Pennridge direction

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers

seeing the graph would