Two point charges are fixed on the y axis: a negative point charge q1 = -28 µC at y1 = +0.21 m and a positive point charge q2 at y2 = +0.36 m. A third point charge q = +8.5 µC is fixed at the origin. The net electrostatic force exerted on the charge q by the other two charges has a magnitude of 17 N and points in the +y direction. Determine the magnitude of q2.

Explanation:

Coulomb's force:

where, q and q' are two charges, d is the distance between them and k is the Coulomb constant.

The net force on charge q at origin is 17 N.

5.35 x 10^-5 C

Explanation:

q1 = - 28 micro Coulomb =- 28 x 10^-6 C

q2 = ?

q3 = 8.5 micro Coulomb = 8.5 x 10^-6 C

y1 = 0.21 m

y2 = 0.36 m

q3 is at origin.

Let F1 is the force between q1 and q3 and F2 is the force between q2 and q3.

By use of Coulomb's law, the force between the two charges is given by

Now,

F1 = 48.6 N    .... (1)

Now,

F2 = 590277.78 q2   .... (2)

Now, F1 - F2 = 17

48.6 - 590277.78 q2 = 17     from (1) and (2)

q2 = 5.35 x 10^-5 C

Thus, the charge on q2 is 5.35 x 10^-5 C.  

given data:

determine the horse power (h.p) = ?

force applied to move the box(f) = 10 pounds,

box lifted from a distance         (d) = 3 feet

time taken to lift                         (t) = 10 sec,

the horse power is defined as amount of work required to move a load. the horse power is equal to 550 foot-pound per second

                  1 h.p   = 550 foot-pound/second

it can also be defined as the the load that need to be move a body for certain distance in a certain amount of time.

mathematically,

                      h.p = (force × distance)/ time

                            = (10 × 3)/ 10

                            = 30/10

                            = 3 foot -pound/sec

hence, the horse power is needed to move the box is 3 foot-pound/second

important note: 1 h.p = 550 foot-pound/second = 746 watts