(a) The force exerted by the electric field on the plastic sphere is equal to

where

is the charge of the sphere and E is the strength of the electric field. This force should balance the weight of the sphere:

where m is the mass of the sphere and g is the gravitational acceleration.
Since the two forces must be equal, we have:

and so we find the intensity of the electric field

(b) Now let's find the direction of the field. The electric force must balance the weight of the sphere, which is directed downward, so the electric force should be directed upward. Since the charge is negative, the force is opposite to the electric field direction, and so the direction of the electric field is downward.
Let V = the volume of the balloon
Force of gravity = V * ?hot * g downward
Buoyant force = V * ?cool * g upward
Net upward force F = V * ?cool * g - V * ?hot * g
F = V g (?cool - ?hot)
Mass of the balloon m = V ?hot
a = F/m = V g (?cool - ?hot)/(V ?hot)
a = g(?cool/?hot - 1)
a = 9.8(1.29/0.93 - 1)
a = 3.79 m/s^2
<span>Answer is 3.79 m/s^2</span>
Answer: Primary coil
A Step-down transformer is an electrical device which is used to decrease the voltage using magnetic induction. The windings of the primary coil are more than the windings of the secondary coils. h1, h2 notations are used to refer to primary coils. On the other hand, x1, x2 notations are used to refer to the secondary coils of the transformer. In case of step-up transformer, the windings of primary coil are less than the secondary in order to increase the voltage.