Answer:
Mechanical waves are waves that require a medium. This means that they have to have some sort of matter to travel through. These waves travel when molecules in the medium collide with each other passing on energy. One example of a mechanical wave is sound.
Answer:
no material that were once part of living things
In 16 times
KE= o.5 m times V squared
Answer:
B 14.5 m/s to the east
Explanation:
We can solve this problem by using the law of conservation of momentum.
In fact, if the system is isolated, the total momentum of the system must be conserved.
Here the total momentum before the stuntman reaches the skateboard is:

where
M = 72.0 kg is the mass of the stuntman
v = 15.0 m/s is his initial velocity (to the east)
The total momentum after the stuntmen reaches the skateboard is:

where
m = 2.50 kg is the mass of the skateboard
v' is the final velocity of the stuntman and the skateboard
Since momentum must be conserved, we have

And solvign for v',

And since the sign is the same as v, the direction is the same (to the east).