The work done by the battery is equal to the charge transferred during the process times the potential difference between the two terminals of the battery:

where q is the charge and

is the potential difference.
In our problem, the work done is W=39 J while the potential difference of the battery is

, so we can find the charge transferred by the battery:
Answer:
W = 0.49 N
τ = 0.4851 Nm
Force
Explanation:
The weight force can be found as:
W = mg
W = (0.05 kg)(9.8 m/s²)
<u>W = 0.49 N</u>
The torque about the pivot can be found as:
τ = W*d
where,
τ = torque
d = distance between weight and pivot = 99 cm = 0.99 m
Therefore,
τ = (0.49 N)(0.99 m)
<u>τ = 0.4851 Nm</u>
The pivot exerts a <u>FORCE </u>on the meter stick because the pivot applies force normally over the stick and has a zero distance from stick.
Answer:

Explanation:
As in any sample you will have 75.8% of Cl-35 iosotopes and 24.3% of Cl-37 iosotopes you can get the average atomic mass as:
