A) leaving a copper penny in vinegar until it turns green
Answer:

Explanation:
In this question we have given
mass of airplane=.6 Kg
Radius of horizontal circle,r=6m
Time taken to complete 1.6 revolution=5s
Therefore time taken to complete 1 revolution, t=
t=3.1 s
We have to find the speed of airplane
We will first find the distance covered by airplane in tracing one circle which is equal to circumference of circle
We know that
Circumference,d = 
or 

We know that speed=
............(1)
Put value of d and t in equation 1
speed=
