209 km/h = 58.0 m/s
2as = v² - u²
Assuming the ball started from rest,
a = (58)² / 2 x 0.11
a = 15,290 m/s²
In a parallel circuit, the equivalent resistance is the reciprocal of (the sum of the individual reciprocals).
1/R = 1/10 + 1/21 + 1/13
1/R = 0.225 mhos
R = 4.45 ohms
I = V / R
The total current out of the battery is
I = (9v)/(4.45ohms)
I = 2.02 Amperes
As the total current leaves the battery, it splits into 3 paths, and each resistor gets part of it. The 10ohm resistor gets the most current; the 21ohm resistor gets the least current. After flowing through the resistors, the 3 currents join and add up to 2.02 Amperes again, and the same current returns to the battery.
Each resistor has the same 9v of EMF across it.
Under free fall, the object is falling with a velocity that is increasing uniformly. Since the gradient of position-time graph reflects the velocity, the gradient is increasing, i.e. curve.
Judging on the fact that this is middle school physics, I would say that it is a beneficial relationship.
