Question

1 Balloons 60 cm Two similar helium-filled balloons tied to a 5 g mass float in equilibrium as shown in the diagram. There is a charge Q on each balloon (a) Draw a free body diagram of the mass and of each balloon three diagrams in total. Clearly label all of the forces in each diagram (b) Determine the charge Qon each balloon 5 g

Answer 1

Here, for the mass, we have

2Tcos$\theta$ = mg

from the diagram

we will use sin theta here

sin theta = opposite / hypotenuse

where opposite = 0.6/2 = 0.3

hypotenuse is 1 m

$\theta$ = arcsin (0.3/1)

$\theta$ = 17.5 degree

so,

T = 5e-3 * 9.8 / 2 * cos 17.5

T = 0.0256829 N

Now, in equilibrium

F = Tsin$\theta$

kq1q2 / r² = Tsin$\theta$

9e9 * q² / 0.6² = 0.0256829 * (0.3 / 1)

q = 0.555e-6 C

or

q = 0.555 uC