Which vector best represents the net force acting on +3c charge in the diagram?
a
b
c
d

-- The two negative charges both attract the positive charge at the origin.

-- The -4C charges are horizontally symmetrical, so there's no net horizontal force on the +3C at the origin.

-- However, the -4C both pull it down.

-- So the net force on the +3C at the origin is directed straight down.

The arrow labelled ' C ' represents the net force on it.

powerful computers now, not then

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.