Answer:
medium
Examples:
A medium is a thing that the sound wave would travel through, like sound waves traveling through air. A mechanical wave cannot travel without a medium, like if the wave were trying to travel through a vacuum.
Answer:
175s
Explanation:
time it takes sunlight to reach the earth in vacuum
C=light speed=299792458m/s
X=1.5x10^8km=1.5x10^11m
c=X/t
T1=X/c
T1=1.5X10^11/299792458=500.34s
time it takes sunlight to reach the earth in water:
First we calculate the speed of light in water taking into account the refractive index
Cw=299792458m/s/1.349=222233104.5m/s
T2=1.5x10^11/222233104.5m/s=675s
additional time it would take for the light to reach the earth
ΔT=T2-T1=675-500=175s
Assuming north as positive direction, the initial and final velocities of the ball are:

(with negative sign since it is due south)

the time taken is

, so the average acceleration of the ball is given by

And the positive sign tells us the direction of the acceleration is north.
Answer:
Option B

Explanation:
Given information
Radius of container, r=12cm=12/100=0.12m
Angular velocity= 2 rev/s, converted to rad/s we multiply by 2π
Angular velocity, 
We know that speed, 
Centripetal acceleration,
and substituting
we obtain that

Substituting \omega for 12.56637061 and r for 0.12

Rounded off, 
F=ma
a=(v2-v1)/(t2-t1)
a=(6-0)/(12-0)
a=6/12
a= .5 m/s^2
f=2300kg*.5m/s^2
f=1150N
f=1200N if using correct sig figs