The really good answer is 30cm CER format
Newton's First Law states that an object would remain at rest or in uniform motion in a straight line unless an unbalanced force acts upon it. So the speed would be the one that remains constant.
Air caught in the ball of foil makes the ball less dense than water
F=ma**2
a=sqrt (F/m)
a=sqrt8.3, which approximately is 3.
So acceleration equals 3 meters per sec**2.
Your question should includes how much energy does the battery deliver in 80 hours interval.
Answer:
The battery delivers 17,280 J
Explanation:
Starting voltage v1 = 9V
Final voltage v2 = 6V = voltage drop after 80hrs
v = v1 - v2 = 9 - 6 = 3V
Electrical current (i) = 20[mA] = 20*10^-3 A
Discharging time = 80 Hrs = 80*(60*60) sec = 288,000 sec
Work done = energy (W) = p.t
Where p = v*i
W = v*i*t
W = 3*(20*10^-3)*288,000
W = 17,280 J
The battery delivers 17,280 J