Two identical conducting small spheres are placed with their centers 0.395 m apart. one is given a charge of -12.0 nc and the other a charge of -15.0 nc.
(a) find the electric force exerted by one sphere on the other.(magnitude)
(b) the spheres are connected by a conducting wire. find the electric force each exerts on the other after they have come to equilibrium. (magnitude)

Answer :

(a). The magnitude of the electric force exerted by one sphere on the other is

(b). The  electric force each exerts on the other after they have come to equilibrium is

Explanation:

Given that,

Distance = 0.395 m

Charge of first sphere = -12.0 nC

Charge of second sphere = -15.0 nC

(a). We need to calculate the magnitude of the electric force exerted by one sphere on the other

Using formula of electric force

Where,

r = distance

Put the value into the formula

(b). The identical spheres are connected by a conducting wire.

Both charges are same so the force is repulsive.

We need to calculate the net charge

Using formula of charge

Put the value into the formula

We need to calculate the magnitude of the electric force each exerts on the other after they have come to equilibrium

Using formula of electric force

Put the value into the formula

Hence, (a). The magnitude of the electric force exerted by one sphere on the other is

(b). The electric force each exerts on the other after they have come to equilibrium is

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west