Interactive solution 6.39 presents a model for solving this problem. a slingshot fires a pebble from the top of a building at a speed of 13.0 m/s. the building is 23.0 m tall. ignoring air resistance, find the speed with which the pebble strikes the ground when the pebble is fired (a) horizontally, (b) vertically straight up, and (c) vertically straight down.

Given that

u = 13 m/s

h= 23 m

a) horizontally

We know that acceleration due top gravity is in vertical direction.

v²=u'²+ 2 g h    ( u'= 0 )

v² = 2 x 9.81 x 23

v= 21.24 m/s  ( vertical direction)

In the horizontal direction

u = 13 m/s

The resultant velocity

V²=v²+u²

V²=21.24²+13²

V= 24.91 m/s

(b) vertically straight up

u= 13 m/s

v²=u²+ 2 g h

v²=13²+ 2 x 9.81 x 23

v= 24.91 m./s

c)vertically straight down.

u= 13 m/s

v²=u²+ 2 g h

v²=13²+ 2 x 9.81 x 23

v= 24.91 m./s

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia