Answer:
0.9m/s^2 (yours is 0.87, so choose that)
Explanation:
formula for centripetal acceleration:
v^2/r
to find v, we know that f=1/90s, and r=180m.
v=(2pir)/T
v=(2pi(180))/90
v=12.6m/s
now plug into a=v^2/r
a=(12.6)^2/180
a=0.9m/s^2
The material in which a wave travels is called a medium. Hope this helps!