A medium is a substance or material that carries the wave. Sounds waves need a medium in order to travel through a wave to help it travel as it cannot travel through a vacuum. Mechanical waves need a medium to transport energy.
Answer:
17640
Explanation:
Power = workdone/time
Power = (force x displacement)/time
Power = (mg x 60)/60
Power = (1800 x 9.8 x 60)/60
=> power = 17640 watt
Is there a question in here somewhere?
Answer:
Explanation:
Since there is no friction angular momentum is conserved. The formula for angular momentum thet will be useful in this case is 
. If we call 1 the situation when the student is at the rim and 2 the situation when the student is at 
from the center, then we have:
Or:
And we want to calculate:
The total moment of inertia will be the sum of the moment of intertia of the disk of mass 
and radius 
, which is 
, and the moment of intertia of the student of mass 
at position 
(which will be 
or ) will be 
, so we will have:
or:
which for our values is:
